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Sample records for dem austenitischen stahl

  1. [Stahl, Leibniz, Hoffmann and breathing].

    Science.gov (United States)

    Carvallo, Sarah

    2006-01-01

    At the beginning of the XVIII th century, Wilhelm Gottfried Leibniz and Friedrich Hoffmann criticize Georg Ernst Stahl's medical theory. They differenciate between unsound and true reasonings. Namely, they validate Stahl's definition of breath but extracting it from its animist basis and placing it in an epistemology obeying to the principle of sufficient reason and to the mechanical model. The stahlian discovery consists in understanding breath as a calorific ventilation against the ancient conception; the iatromechanists recognize its accuracy, but they try then to transpose it to a mechanical model of ventilation. Using it in a different epistemological context implies that they analyze the idea of discovery "true" in its contents, but "wrong" in its hypothesis. It impels to examine the epistemology of medical knowledge, as science and therapeutics, and in its links with the other scientific theories. Thus, if Leibniz as philosopher and Hoffmann as doctor consider Stahl's animism so important, it is because its discoveries question the fundamental principles of medicine.

  2. Handbuch Stahl Auswahl, Verarbeitung, Anwendung

    CERN Document Server

    Bleck, Wolfgang

    2018-01-01

    Stahl ist der wichtigste Konstruktionswerkstoff. Im Maschinen- und Anlagenbau, Fahrzeugbau, Schiffbau, Stahlbau und in vielen anderen Industriebereichen ist er durch keinen anderen Werkstoff zu ersetzen. Für jeden Anwendungszweck gibt es passende Stahlsorten am Markt zu kaufen. Die Feinabstimmung der gewünschten Eigenschaften kann im weiteren Verarbeitungsprozess vorgenommen werden, bis der Werkstoff optimal den gewünschten Produktanforderungen entspricht. Die Anzahl der Möglichkeiten ist sehr groß und somit auch die Schwierigkeit, den genau passenden Stahl zu finden bzw. zu erzeugen. Das vorliegende Handbuch hilft Ihnen, dieses Problem zu lösen. Es zeigt u.a. - mit welchen systematischen Ansätzen und Hilfsmitteln Sie die in Frage kommende Stahlsorte eingrenzen können - die wichtigsten produktrelevanten Eigenschaften und Lieferformen - die werkstoffgerechte Weiterverarbeitung durch umformende und spanende Fertigungsprozesse und Wärmebehandlung - hunderte Anwendungsbeispiele aus Maschinen- und Anlage...

  3. Optimierung einer Fachwerkbinderkonstruktion in Stahl- bzw. kombinierter Stahl-Holzbauweise unter Berücksichtigung brandschutztechnischer Anforderungen am Beispiel einer Sporthalle

    OpenAIRE

    Sandbrink, Stefan

    2017-01-01

    Die Dachtragwerke von wettkampftauglichen Sporthallen müssen in der Regel neben dem Sportfeldbereich auch den Tribünenbereich stützenfrei überspannen. Aufgrund der großen Spannweite von mehr als 28 Metern kann dieser Forderung bspw. durch Dachbinder in Stahl-, Holz- oder Spannbetonbauweise entsprochen werden, welche nach der Niedersächsischen Versammlungsstättenverordnung zudem feuerhemmend ausgebildet sein müssen. Im Rahmen dieser Arbeit sollen Dachbinder in Stahlbzw. hybrider Stahl-Holzbauw...

  4. Investigations on avoidance of hot cracks during laser welding of austenitic Cr-Ni steels and nickel-based alloys using temperature field tailoring. Final report; Untersuchungen zur Vermeidung von Heissrissen beim Laserstrahlschweissen von austenitischen Cr-Ni-Staehlen und Nickelbasislegierungen mittels Temperaturfeld-Tailoring. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-08

    The aim of the project was to transfer the developed method of laser beam welding of heat treated machining steels of temperature field tailoring on hot crack endangered austenitic Cr-Ni steels and nickel-based alloys. With this method, transient thermal stresses adjacent to the weld are produced by an travelling induction heating so that the hot cracking is prevented during welding. As test materials the austenitic Cr-Ni steel with sulfur additive 1.4305, the Cr-Ni steels 1.4404 and 1.4435 and the nickel-based alloy Udimet 720 were selected. As a result of the research it was shown that a hot crack-free laser welding in the investigated materials using at least three different welding and material-technical approaches is possible. [German] Das Ziel des Forschungsvorhabens bestand darin, das fuer das Laserstrahlschweissen verguetbarer Automatenstaehle entwickelte Verfahren des Temperaturfeld-Tailorings auf heissrissgefaehrdete austenitische Cr-Ni-Staehle und Nickelbasislegierungen zu uebertragen. Mit diesem Verfahren werden waehrend des Schweissens transiente thermische Spannungen neben der Schweissnaht durch eine mitlaufende induktive Erwaermung so erzeugt, dass die Heissrissbildung verhindert wird. Als Versuchswerkstoffe wurden der austenitische Cr-Ni-Stahl mit Schwefelzusatz 1.4305, die Cr-Ni-Staehle 1.4404 und 1.4435 sowie die Nickelbasislegierung Udimet 720 ausgewaehlt. Im Ergebnis des Forschungsvorhabens konnte gezeigt werden, dass ein heissrissfreies Laserstrahlschweissen bei den untersuchten Werkstoffen unter Nutzung von mindestens drei verschiedenen schweiss- und werkstofftechnischen Ansaetzen moeglich ist: Erstens koennen mit einem Temperaturfeld-Tailoring bei im Stumpfstoss zu verschweissenden Blechen aus austenitischen Staehlen bis mindestens 6 mm Dicke senkrecht zur Naht und parallel zur Blechoberflaeche wirkende transiente Druckspannungen erzeugt werden, die der Bildung von Mittelrippenrissen oder dazu parallel liegenden Heissrissen entgegenwirken

  5. L'ordre et l'existence: Stahl et les fondements du droit politique moderne

    DEFF Research Database (Denmark)

    Lev, Amnon

    2010-01-01

    Artiklen leverer Amnon Lev en nyfortolkning af Friedrich Julius Stahls værk og dets betydning for den moderne statsforfatningsret. Stahl er den største statstænker i det 19. århundrede og et af århundredets vigtigste retsfilosoffer. I artiklen vises det, 1) hvorledes Stahl løser statsforfatningsr...

  6. Paul Henri Stahl and His Contribution to European Ethnosociology

    Directory of Open Access Journals (Sweden)

    GHEORGHE ŞIŞEŞTEAN

    2009-02-01

    Full Text Available Only a little while has passed since the death of Professor Paul H. Stahl. These lines are an attempt at a synthetic presentation of his life and scientific activity, including short fragments from his memories related to the fieldwork he conducted in his early life, most of the times together with his friend and collaborator, Paul Petrescu. At the same time, being well acquainted with his ethnological and sociological views, as a former student of Paul H. Stahl at the EHESS in Paris, I have sought to capture some of the theoretical dimensions of his activity, insisting first of all on his important contribution to a European anthropology of premodern forms of property and organization of social groups. Within this European analytical and contrastive framework, I have also integrated the Romanian case, to which the late professor Paul H. Stahl was so attached. Secondly, I outlined several directions of analysis of what we could call anthropology of the sacred, the way in which the sacred forms an important dimension of social organization in European peasant societies.

  7. Stahl et les âges de la vie

    Directory of Open Access Journals (Sweden)

    Sarah Carvallo

    2011-07-01

    Full Text Available La vieillesse constitue une pierre de touche pour toute théorie médicale : elle oblige à rendre raison de la temporalité à l’œuvre dans la vie. Aux yeux de Stahl, les iatromécaniciens méconnaissent la dimension temporelle de l’organisme ; en particulier, ils en ignorent la périodicité. Comprendre la vieillesse suppose donc la critique de la représentation linéaire du temps organique, que développe la mécanique et qui réduit le vivant au seul composé physique et chimique. Il reste alors à trouver la cause de la périodicité organique : sur ce point, Georg Ernst Stahl critique Thomas Sydenham, qui reconnaît certes la périodicité du vivant mais nie la possibilité d’une médecine étiologique. Pour sa part, le médecin de Halle cherche à rendre compte du vieillissement en lien avec les actions organiques fondamentales : le tonus, la circulation, l’excrétion, la sécrétion.

  8. Motus Tonicus: Georg Ernst Stahl's formulation of tonic motion and early modern medical thought.

    Science.gov (United States)

    Chang, Ku-Ming

    2004-01-01

    This paper places in multiple contexts Stahl's formulation of tonic motion, a contractive and relaxative movement of body tissues that was thought to moderate the circulatory blood flowing through their porous structure. The paper analyzes Stahl's theory, elucidates its role in connecting his physiology and pathology, and situates its formulation in his conceptual development as well as the intellectual history of early modern medicine. The theory was at first a post-Harveyan attempt to explain occasional uneven blood flows; it was then expanded to account for the mechanism of blood circulation and metabolism, and formed a fundamental part of Stahl's effort to present a theory of animal heat and fever that would replace the traditional Galenic and fermentational theories. Tonic motion constituted the most important device that counteracted the ineluctable, unceasing corruption of the body, as dictated by its chemical nature; it thus qualified as the preeminent form of what Stahl considered vital motions.

  9. Evidence of cracks in austenitic pipe weldings with a radiometric inspection system; Nachweis von Rissen in austenitischen Rohrleitungsnaehten mit einem radiometrischen Pruefsystem

    Energy Technology Data Exchange (ETDEWEB)

    Maier, H.J.; Wuensch, W. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1999-08-01

    The paper reports the development of a radiometric prototype device and its application to inspection of austenitic weldings with intercrystalline crack defects. The device initially was intended to be used for supplemental inspection for clarification of contradictory or unclear testing results, but the results obtained justify to consider the possibility of using it as an independent, full-scope testing instrument. (orig./CB) [Deutsch] Berichtet wird ueber die Entwicklung eines Prototypes eines Radiometrie-Geraetes zur Pruefung von austenitischen Schweissnaehten mit interkristalliner Rissbildung, zunaechst als Entscheidungshilfe bei unklaren bzw. sich widersprechenden Pruefresultaten. Zwischenzeitlich wird auch daran gedacht, ein solches Geraet fuer eine vollstaendige Pruefung weiter zu entwickeln. (orig./DGE)

  10. 1 küsimus noorele juhile : Said just juhiks. Millest tuleks alustada? / Gert Stahl, Erki Kert, Madis Talmar ... [jt

    Index Scriptorium Estoniae

    2009-01-01

    Juhtimisküsimusele vastavad EASi rahvusvahelistumise divisjoni direktor, riskikapitali ettevõtte G.S.I. Ventures juhatuse esimees ning moefirma Bastion nõukogu esimees Gert Stahl, LHV juhatuse liige ja LHV ettevõtete nõustamise valdkonna juht Erki Kert, Tallinna Tehnikaülikooli tudeng ja mitmete üliõpilasprojektide juht Madis Talmar, filmitootmisfirma Alexandra Film produtsent Marianne Ostrat, ettevõtluskonsultant Liina Joller ning konsultatsioonifirma BDA Consulting juht Lo Rihvk

  11. kawaihae_dem.grd

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to...

  12. Coastal Digital Elevation Models (DEMs)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digital elevation models (DEMs) of U.S. and other coasts that typically integrate ocean bathymetry and land topography. The DEMs support NOAA's mission to understand...

  13. How to merge a DEM?

    NARCIS (Netherlands)

    Reuter, H.I.; Strobl, P.; Mehl, W.

    2011-01-01

    A DEM is one of the most useful information for spatial modelling and monitoring. Several DEMs have been published in the public domain like SRTM and ASTER GDEM with and without considering the horizontal and vertical misallocation of single input data. Results of that are for example the inherent

  14. DEM generation from contours and a low-resolution DEM

    Science.gov (United States)

    Li, Xinghua; Shen, Huanfeng; Feng, Ruitao; Li, Jie; Zhang, Liangpei

    2017-12-01

    A digital elevation model (DEM) is a virtual representation of topography, where the terrain is established by the three-dimensional co-ordinates. In the framework of sparse representation, this paper investigates DEM generation from contours. Since contours are usually sparsely distributed and closely related in space, sparse spatial regularization (SSR) is enforced on them. In order to make up for the lack of spatial information, another lower spatial resolution DEM from the same geographical area is introduced. In this way, the sparse representation implements the spatial constraints in the contours and extracts the complementary information from the auxiliary DEM. Furthermore, the proposed method integrates the advantage of the unbiased estimation of kriging. For brevity, the proposed method is called the kriging and sparse spatial regularization (KSSR) method. The performance of the proposed KSSR method is demonstrated by experiments in Shuttle Radar Topography Mission (SRTM) 30 m DEM and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) 30 m global digital elevation model (GDEM) generation from the corresponding contours and a 90 m DEM. The experiments confirm that the proposed KSSR method outperforms the traditional kriging and SSR methods, and it can be successfully used for DEM generation from contours.

  15. Attempts to improve the fatigue characteristics of the austenitic steel X5CrNi18-10 in the temperature range of 25-600 C by mechanical boundary layer hardening; Zur Verbesserung des Ermuedungsverhaltens des austenitischen Stahls X5CrNi18-10 im Temperaturbereich 25-600 C durch mechanische Randschichtverfestigungsverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, Ivan

    2007-01-31

    Pieces of the austenitic steel X5CrNi18-10 whose boundary layers had been hardened by different methods were investigated with a view to their fatigue deformation characteristics in the temperature range of 25-600 degC. Parallel to this, microstructural and X-ray analyses provided deeper understanding of fatigue deformation. The microstructure was characterized, among others, by TEM. Boundary layers were solidified by rolling, by a combination of mechanical and thermal processes, by high-temperature rolling, and by laser shock solidification. The analyses focused on microstructural processes and on the intrinsic stress stability and provided important information on the fabrication of structural components with optimised life. (orig.)

  16. Progress report on a NDT round robin on austenitic circumferential pipe welds; Fortschrittsbericht ueber einen ZfP-Ringversuch an austenitischen Rohrleitungs-Rundschweissnaehten

    Energy Technology Data Exchange (ETDEWEB)

    Brast, G. [Preussische Elektrizitaets-AG (Preussenelektra), Hannover (Germany); Maier, H.J.; Knoch, P.; Mletzko, U. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1998-11-01

    The objective of the project is establish on the basis of Round Robin tests the current state of efficiency of various, defined testing methods, so that required or achievable optimizations can be defined and made. The project work up to date encompasses mon-destructive examinations of 15 austenitic welds with nominal widths DN 150/200/250 and wall thicknesses from 8 to 18 mm. Except for one test piece, (elbow/elbow), the joining welds are straight pipe to elbow welds. The results of the Round Robin tests show that the NDE detection limits for the fault examined (intercrystalline stress corrosion cracking) are in the range assumed so far, i.e. from about 20 to 25% of the wall thickness to be examined. The defect detection rates of the ultrasonic test methods applied are approx. 70% and thus are about equal in achievement with comparable international Round Robin tests (PISC; ASME/PDI, ENIQ, etc.). Clearly better are the fault detection rates of radiography. Evaluation of the individual results indicates the detection limits can be improved, by 1. reducing the misalignment of edges, 2. grinding of welds, 3. avoiding sharp notches at the root, 4. producing coaxial surfaces. (orig./CB) [Deutsch] Ein Ziel des Vorhabens ist es, mit Ringversuchen den derzeitigen Stand der Leistungsfaehigkeit einzelner Pruefverfahren und -techniken zu erkennen, um moeglicherweise notwendige Optimierungen vornehmen zu koennen. Das Vorhaben umfasst bis jetzt zerstoerungsfreie Pruefungen an 15 austenitischen Naehten mit Nennweiten DN 150/200/250 und Wandstaerken zwischen 8 und 18 mm. Mit einer Ausnahme (Bogen/Bogen) handelt es sich um Verbindungen Geradrohr/Bogen. Die Ergebnisse des Ringversuches weisen darauf hin, dass die Nachweisgrenzen der ZfP fuer den vorliegenden Fehlertyp (Interkristalline Spannungsrisskorrosion) in der bisher schon angenommenen Groessenordnung von ca. 20-25% der geprueften Wanddicke liegen. Die Fehlerauffind-Raten der US-Pruefung liegen mit ca. 70% im Rahmen

  17. Mit dem Makel der Kollaboration

    OpenAIRE

    Hajduk, Thomas

    2006-01-01

    Vor 200 Jahren wurde der Rheinbund gegründet. Erst in ihm entstanden die Grundlagen des modernen deutschen Föderalismus. (http://www.welt.de/print-welt/article228798/Mit-dem-Makel-der-Kollaboration.html)

  18. Literary Returns: HENRIETTE YVONNE STAHL or the Fate of an Exceptional Woman to the Backdrop of Dramatic History

    Directory of Open Access Journals (Sweden)

    Constanţa-Valentina MIHĂILĂ

    2013-01-01

    Full Text Available The history of the Romanian literature includes writers who, without being leading writers, have modern readers and success on the market. Henriette Yvonne Stahl crossed almost whole 20th century, with all his historical events, wrote nine novels, two volumes of short novels, a volume of poems and performed the translation of ten masterpieces from eight writers. Although she was native French speaker, the writer has created only in Romanian language and never ceased on being Romanian citizen. The men from her life, Ion Vinea and Petru Dumitriu, had in her an incentive of their talent and a formidable critic. The disease was the background of her existence, but this did not spare her from the communist prison experience. Without being enroll in some literary circle or some fancy literary orientation, without writing memories or being diarist, she spread her ego and her experiences throughout his entire opera, and she kept her aristocratic halo and her principles till the end of her life.

  19. Demência de alzheimer

    OpenAIRE

    Galvão, Ana Maria

    2011-01-01

    A doença de Alzheimer é considerada a demência mais comum no ser humano, sendo caraterizada como um distúrbio degenerativo do cérebro que leva à perda de memória (Alzheimer's Association, 2010). A notícia de um diagnóstico de demência causa um intenso impacto na vida de pacientes e familiares. Os principais motivos referem-se à impossibilidade de cura e à progressão por vezes rápida dos sintomas. São comumente evidenciadas reações emocionais negativas envolvendo impotência, medo e...

  20. `Dem DEMs: Comparing Methods of Digital Elevation Model Creation

    Science.gov (United States)

    Rezza, C.; Phillips, C. B.; Cable, M. L.

    2017-12-01

    Topographic details of Europa's surface yield implications for large-scale processes that occur on the moon, including surface strength, modification, composition, and formation mechanisms for geologic features. In addition, small scale details presented from this data are imperative for future exploration of Europa's surface, such as by a potential Europa Lander mission. A comparison of different methods of Digital Elevation Model (DEM) creation and variations between them can help us quantify the relative accuracy of each model and improve our understanding of Europa's surface. In this work, we used data provided by Phillips et al. (2013, AGU Fall meeting, abs. P34A-1846) and Schenk and Nimmo (2017, in prep.) to compare DEMs that were created using Ames Stereo Pipeline (ASP), SOCET SET, and Paul Schenk's own method. We began by locating areas of the surface with multiple overlapping DEMs, and our initial comparisons were performed near the craters Manannan, Pwyll, and Cilix. For each region, we used ArcGIS to draw profile lines across matching features to determine elevation. Some of the DEMs had vertical or skewed offsets, and thus had to be corrected. The vertical corrections were applied by adding or subtracting the global minimum of the data set to create a common zero-point. The skewed data sets were corrected by rotating the plot so that it had a global slope of zero and then subtracting for a zero-point vertical offset. Once corrections were made, we plotted the three methods on one graph for each profile of each region. Upon analysis, we found relatively good feature correlation between the three methods. The smoothness of a DEM depends on both the input set of images and the stereo processing methods used. In our comparison, the DEMs produced by SOCET SET were less smoothed than those from ASP or Schenk. Height comparisons show that ASP and Schenk's model appear similar, alternating in maximum height. SOCET SET has more topographic variability due to its

  1. Digtial Elevation Model (DEM) 250K

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital Elevation Model (DEM) is the terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a...

  2. Digitial Elevation Model (DEM) 100K

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital Elevation Model (DEM) is the terminology adopted by the USG to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a...

  3. Digital Elevation Model (DEM) 24K

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital Elevation Model (DEM) is the terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a...

  4. BLAZE-DEM: A GPU based Polyhedral DEM particle transport code

    CSIR Research Space (South Africa)

    Govender, Nicolin

    2013-05-01

    Full Text Available This paper introduces the BLAZE-DEM code that is based on the Discrete Element Method (DEM) and specifically targeted for Graphical Processing Unit (GPU) platforms. BLAZE-DEM uses actual polyhedral particle representations as opposed to multi...

  5. ArcticDEM Validation and Accuracy Assessment

    Science.gov (United States)

    Candela, S. G.; Howat, I.; Noh, M. J.; Porter, C. C.; Morin, P. J.

    2017-12-01

    ArcticDEM comprises a growing inventory Digital Elevation Models (DEMs) covering all land above 60°N. As of August, 2017, ArcticDEM had openly released 2-m resolution, individual DEM covering over 51 million km2, which includes areas of repeat coverage for change detection, as well as over 15 million km2 of 5-m resolution seamless mosaics. By the end of the project, over 80 million km2 of 2-m DEMs will be produced, averaging four repeats of the 20 million km2 Arctic landmass. ArcticDEM is produced from sub-meter resolution, stereoscopic imagery using open source software (SETSM) on the NCSA Blue Waters supercomputer. These DEMs have known biases of several meters due to errors in the sensor models generated from satellite positioning. These systematic errors are removed through three-dimensional registration to high-precision Lidar or other control datasets. ArcticDEM is registered to seasonally-subsetted ICESat elevations due its global coverage and high report accuracy ( 10 cm). The vertical accuracy of ArcticDEM is then obtained from the statistics of the fit to the ICESat point cloud, which averages -0.01 m ± 0.07 m. ICESat, however, has a relatively coarse measurement footprint ( 70 m) which may impact the precision of the registration. Further, the ICESat data predates the ArcticDEM imagery by a decade, so that temporal changes in the surface may also impact the registration. Finally, biases may exist between different the different sensors in the ArcticDEM constellation. Here we assess the accuracy of ArcticDEM and the ICESat registration through comparison to multiple high-resolution airborne lidar datasets that were acquired within one year of the imagery used in ArcticDEM. We find the ICESat dataset is performing as anticipated, introducing no systematic bias during the coregistration process, and reducing vertical errors to within the uncertainty of the airborne Lidars. Preliminary sensor comparisons show no significant difference post coregistration

  6. Estimating Coastal Digital Elevation Model (DEM) Uncertainty

    Science.gov (United States)

    Amante, C.; Mesick, S.

    2017-12-01

    Integrated bathymetric-topographic digital elevation models (DEMs) are representations of the Earth's solid surface and are fundamental to the modeling of coastal processes, including tsunami, storm surge, and sea-level rise inundation. Deviations in elevation values from the actual seabed or land surface constitute errors in DEMs, which originate from numerous sources, including: (i) the source elevation measurements (e.g., multibeam sonar, lidar), (ii) the interpolative gridding technique (e.g., spline, kriging) used to estimate elevations in areas unconstrained by source measurements, and (iii) the datum transformation used to convert bathymetric and topographic data to common vertical reference systems. The magnitude and spatial distribution of the errors from these sources are typically unknown, and the lack of knowledge regarding these errors represents the vertical uncertainty in the DEM. The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) has developed DEMs for more than 200 coastal communities. This study presents a methodology developed at NOAA NCEI to derive accompanying uncertainty surfaces that estimate DEM errors at the individual cell-level. The development of high-resolution (1/9th arc-second), integrated bathymetric-topographic DEMs along the southwest coast of Florida serves as the case study for deriving uncertainty surfaces. The estimated uncertainty can then be propagated into the modeling of coastal processes that utilize DEMs. Incorporating the uncertainty produces more reliable modeling results, and in turn, better-informed coastal management decisions.

  7. Automated Quality Control for Ortholmages and DEMs

    DEFF Research Database (Denmark)

    Höhle, Joachim; Potucková, Marketa

    2005-01-01

    The checking of geometric accurancy of orthoimages and digital elevation models (DEMs) is discussed. As a reference, an existing orthoimage and a second orthoimage derived from an overlapping aerial image, are used. The proposed automated procedures for checking the orthoimages and DEMs are based...... for the maximum correlation coefficient, the average mutual information, and distancecan reduce the number of blunders in the automated measurements considerably and should therefore be applied. The calculation of DEM errors is carried out by an improved formula. The new methods and procedures are applied to two...

  8. 2014 USACE NCMP Topobathy Lidar DEM: Oregon

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These Digital Elevation Model (DEM) files contain rasterized topobathy lidar elevations at a 1 m grid size, generated from data collected by the Coastal Zone Mapping...

  9. 2016 USGS Lidar DEM: Maine QL2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Product: These are Digital Elevation Model (DEM) data for Franklin, Oxford, Piscataquis, and Somerset Counties, Maine as part of the required deliverables for the...

  10. VT Lidar DEM (1 meter) - 2005 - Essex

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various...

  11. Eine Analyse des Zusammenhangs zwischen dem Konsum von Alkopops und dem Problemverhalten von Jugendlichen

    OpenAIRE

    Metzner, Cornelia Beate Isabel

    2007-01-01

    Zielsetzung: In dieser Arbeit wird untersucht, ob bei Jugendlichen ein Zusammenhang zwischen dem Konsum von Alkopops einerseits und dem sonstigen Alkoholtrinkverhalten, dem Konsum von Zigaretten und illegalen Drogen sowie weiteren Risikoverhaltensweisen andererseits besteht, ferner ob sich Unterschiede im Verhalten von Jungen und Mädchen ergeben. Theoretischer und empirischer Hintergrund: �Alkopops�, d. h. Mischgetränke diverser Hersteller aus Likör bzw. Schnaps und Limonade sowie wein- ...

  12. Landbrugets trædemølle

    DEFF Research Database (Denmark)

    Hansen, Henning Otte

    2016-01-01

    Teorien om landbrugets trædemølle siger, at teknologi medfører stigende produktivitet, stigende udbud og dermed faldende priser. Dermed øges behovet for ny teknologi. Det vedvarende teknologipres gavner de innovative landmænd, mens de mere afventende landmænd kun oplever de negative virkninger i...... form af prisfald. I denne artikel beskrives nærmere de enkelte elementer i trædemøllen. Samtidig vurderes trædemøllens betydning og mulige påvirkning. Det konkluderes, at trædemøllen, dens forudsætninger og afledte virkninger stadig er fuldt gældende. Det er ikke muligt for et enkelt land eller region...... af bremse trædemøllen på lang sigt. På lokalt plan kan man løse nogle sociale og økonomiske problemer skabt af trædemøllen gennem nemmere afvandring....

  13. Large Scale Landform Mapping Using Lidar DEM

    Directory of Open Access Journals (Sweden)

    Türkay Gökgöz

    2015-08-01

    Full Text Available In this study, LIDAR DEM data was used to obtain a primary landform map in accordance with a well-known methodology. This primary landform map was generalized using the Focal Statistics tool (Majority, considering the minimum area condition in cartographic generalization in order to obtain landform maps at 1:1000 and 1:5000 scales. Both the primary and the generalized landform maps were verified visually with hillshaded DEM and an orthophoto. As a result, these maps provide satisfactory visuals of the landforms. In order to show the effect of generalization, the area of each landform in both the primary and the generalized maps was computed. Consequently, landform maps at large scales could be obtained with the proposed methodology, including generalization using LIDAR DEM.

  14. STATISTIC TESTS AIDED MULTI-SOURCE DEM FUSION

    Directory of Open Access Journals (Sweden)

    C. Y. Fu

    2016-06-01

    Full Text Available Since the land surface has been changing naturally or manually, DEMs have to be updated continually to satisfy applications using the latest DEM at present. However, the cost of wide-area DEM production is too high. DEMs, which cover the same area but have different quality, grid sizes, generation time or production methods, are called as multi-source DEMs. It provides a solution to fuse multi-source DEMs for low cost DEM updating. The coverage of DEM has to be classified according to slope and visibility in advance, because the precisions of DEM grid points in different areas with different slopes and visibilities are not the same. Next, difference DEM (dDEM is computed by subtracting two DEMs. It is assumed that dDEM, which only contains random error, obeys normal distribution. Therefore, student test is implemented for blunder detection and three kinds of rejected grid points are generated. First kind of rejected grid points is blunder points and has to be eliminated. Another one is the ones in change areas, where the latest data are regarded as their fusion result. Moreover, the DEM grid points of type I error are correct data and have to be reserved for fusion. The experiment result shows that using DEMs with terrain classification can obtain better blunder detection result. A proper setting of significant levels (α can detect real blunders without creating too many type I errors. Weighting averaging is chosen as DEM fusion algorithm. The priori precisions estimated by our national DEM production guideline are applied to define weights. Fisher’s test is implemented to prove that the priori precisions correspond to the RMSEs of blunder detection result.

  15. S1-Leitlinie Lipödem.

    Science.gov (United States)

    Reich-Schupke, Stefanie; Schmeller, Wilfried; Brauer, Wolfgang Justus; Cornely, Manuel E; Faerber, Gabriele; Ludwig, Malte; Lulay, Gerd; Miller, Anya; Rapprich, Stefan; Richter, Dirk Frank; Schacht, Vivien; Schrader, Klaus; Stücker, Markus; Ure, Christian

    2017-07-01

    Die vorliegende überarbeitete Leitlinie zum Lipödem wurde unter der Federführung der Deutschen Gesellschaft für Phlebologie (DGP) erstellt und finanziert. Die Inhalte beruhen auf einer systematischen Literaturrecherche und dem Konsens von acht medizinischen Fachgesellschaften und Berufsverbänden. Die Leitlinie beinhaltet Empfehlungen zu Diagnostik und Therapie des Lipödems. Die Diagnose ist dabei auf der Basis von Anamnese und klinischem Befund zu stellen. Charakteristisch ist eine umschriebene, symmetrisch lokalisierte Vermehrung des Unterhautfettgewebes an den Extremitäten mit deutlicher Disproportion zum Stamm. Zusätzlich finden sich Ödeme, Hämatomneigung und eine gesteigerte Schmerzhaftigkeit der betroffenen Körperabschnitte. Weitere apparative Untersuchungen sind bisher besonderen Fragestellungen vorbehalten. Die Erkrankung ist chronisch progredient mit individuell unterschiedlichem und nicht vorhersehbarem Verlauf. Die Therapie besteht aus vier Säulen, die individuell kombiniert und an das aktuelle Beschwerdebild angepasst werden sollten: komplexe physikalische Entstauungstherapie (manuelle Lymphdrainage, Kompressionstherapie, Bewegungstherapie, Hautpflege), Liposuktion und plastisch-chirurgische Interventionen, Ernährung und körperliche Aktivität sowie ggf. additive Psychotherapie. Operative Maßnahmen sind insbesondere dann angezeigt, wenn trotz konsequent durchgeführter konservativer Therapie noch Beschwerden bestehen bzw. eine Progredienz des Befundes und/oder der Beschwerden auftritt. Eine begleitend zum Lipödem bestehende morbide Adipositas sollte vor einer Liposuktion therapeutisch angegangen werden. © 2017 The Authors | Journal compilation © Blackwell Verlag GmbH, Berlin.

  16. ASTER Orthorectified Digital Elevation Model (DEM) V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The ASTER L3 DEM and Orthorectified Images form a multi-file product that contains both the Digital Elevation Model (DEM), and the Orthorectified Image products....

  17. MESSENGER MERCURY MDIS LEVEL 5 DEM V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== The MESSENGER MDIS DEMs are derived products. A DEM is a gridded (raster) product that records elevation values of a given terrain in each pixel....

  18. Forest biomass mapping from fusion of GEDI Lidar data and TanDEM-X InSAR data

    Science.gov (United States)

    Qi, W.; Hancock, S.; Armston, J.; Marselis, S.; Dubayah, R.

    2017-12-01

    Mapping forest above-ground biomass (hereafter biomass) can significantly improve our ability to assess the role of forest in terrestrial carbon budget and to analyze the ecosystem productivity. Global Ecosystem Dynamic Investigation (GEDI) mission will provide the most complete lidar observations of forest vertical structure and has the potential to provide global-scale forest biomass data at 1-km resolution. However, GEDI is intrinsically a sampling mission and will have a between-track spacing of 600 m. An increase in adjacent-swath distance and the presence of cloud cover may also lead to larger gaps between GEDI tracks. In order to provide wall-to-wall forest biomass maps, fusion algorithms of GEDI lidar data and TanDEM-X InSAR data were explored in this study. Relationship between biomass and lidar RH metrics was firstly developed and used to derive biomass values over GEDI tracks which were simulated using airborne lidar data. These GEDI biomass values were then averaged in each 1-km cell to represent the biomass density within that cell. Whereas for cells without any GEDI observations, regression models developed between GEDI-derived biomass and TDX InSAR variables were applied to predict biomass over those places. Based on these procedures, contiguous biomass maps were finally generated at 1-km resolution over three representative forest types. Uncertainties for these biomass maps were also estimated at 1 km following methods developed in Saarela et al. (2016). Our results indicated great potential of GEDI/TDX fusion for large-scale biomass mapping. Saarela, S., Holm, S., Grafstrom, A., Schnell, S., Naesset, E., Gregoire, T.G., Nelson, R.F., & Stahl, G. (2016). Hierarchical model-based inference for forest inventory utilizing three sources of information. Annals of Forest Science, 73, 895-910

  19. The role of DEM at CERN

    CERN Document Server

    Van der Bij, E

    2005-01-01

    The DEM group in the Technical Support department provides services for the fabrication of special printed circuits that are invaluable for the whole particle physics community. The capability is based around a core technology that is developed by using skills to etch and process materials that are not commonly used in industry, combined with production methods used in PCB manufacturing. The role of the prototyping facilities is to assist engineers and physicists and to offer them easy access to competencies often not available from industry. At the same time, with the expertise and production capacity available, it makes that CERN is always geared up to handle emergency situations. The design office and the assembly workshop that are also part of DEM have similar roles that lower the cost and improve the quality and maintainability of electronics developed at CERN.

  20. Characterizing solids mixing in DEM simulations

    OpenAIRE

    Godlieb, W.; Deen, N.G.; Kuipers, J.A.M.

    2007-01-01

    In the production and processing of granular matter, solids mixing plays an important role. Granular materials such as sand, polymeric particles and fertilizers are processed in different apparatus such as fluidized beds, rotary kilns and spouted beds. In the operation of these apparatus mixing often plays an important role, as it helps to prevent formation of hot-spots, off-spec products and undesired agglomerates. DEM can be used to simulate these granular systems and provide insight in mix...

  1. Pulse fracture simulation in shale rock reservoirs: DEM and FEM-DEM approaches

    Science.gov (United States)

    González, José Manuel; Zárate, Francisco; Oñate, Eugenio

    2017-11-01

    In this paper we analyze the capabilities of two numerical techniques based on DEM and FEM-DEM approaches for the simulation of fracture in shale rock caused by a pulse of pressure. We have studied the evolution of fracture in several fracture scenarios related to the initial stress state in the soil or the pressure pulse peak. Fracture length and type of failure have been taken as reference for validating the models. The results obtained show a good approximation to FEM results from the literature.

  2. Heinrich Stahli ja Johannes Gutslaffi Uue Testamendi tõlke kõrvutus / An Attempt at the Comparison of the Translations of the New Testament by Heinrich Stahl und Johannes Gutslaff

    Directory of Open Access Journals (Sweden)

    Kristiina Ross

    2012-06-01

    Full Text Available The aim of the article is to compare two 17th century translations of the New Testament: the translation by Heinrich Stahl (1638 and the translation by Johannes Gutslaff (1641–1656. Relying on the model of description presented by Torop (1989 and Torop and Osimo (2010, the translations are described by three aspects (1 linguistic, (2 functional, (3 that of the translator`s position within three different time perspectives: achronic, synchronic and diachronic. Within the achronic perspective, the two translations seem to be quite different in all three aspects. In the case of Stahl´s translation, the original text was Luther´s German translation and the target language was the North-Estonian vernacular. Different parts of the Bible had probably been translated by different persons and Stahl collected them, publishing them in a volume of his church manual. Gutslaff, on the other hand, translated the text himself using the original Greek version. His target language was the South-Estonian vernacular but his work was never published. Within the diachronic perspective, the differences disappear and the two translations seem to be quite similar. From today`s point of view both tr anslations are linguistically archaic and have no functional value except as object s of scientific research. Synchronic description is the most complicated one. The article tries to put to the test the possibilities of describing old translations from the point of view of their translation method. Very few examples of the Estonian language of the 17th century have been preserved, most are translations from German written down by German pastors. In addition to that, researchers know almost nothing about the Estonian language spoken by native speaker s of the time. As a re sult of this, it is hard to evaluate the linguistic status of many constructions and idioms used by the translators. This in turn makes it difficult to evaluate the stylistic intentions of the translator

  3. Dem Higgs-Teilchen auf der Spur

    OpenAIRE

    Schultz-Coulon, Hans-Christian

    2013-01-01

    Es ist ungefähr ein Jahr her - da ging ein freudvoller Aufschrei durch die Physikerwelt. Rund fünf Jahrzehnte nachdem seine Existenz vorausgesagt wurde, schien es tatsächlich gefunden: das sogenannte Higgs-Boson. Ein Teilchen, das zur Erklärung der Masse dient. Heute, viele Experimente später, haben sich die Hinweise nochmal verdichtet, dass es sich tatsächlich um den gesuchten heiligen Gral handelt, von dem Wissenschaftler manchmal sprechen. Das ATLAS-Projekt am Kernforschungszentrum CERN in...

  4. Automated Quality Control for Ortholmages and DEMs

    DEFF Research Database (Denmark)

    Höhle, Joachim; Potucková, Marketa

    2005-01-01

    on matching of corresponding image patches. Existing topographic databases are additionally used in order to select time-invariant objects as checkpoints. In order to avoid blunders in the correlation, thresholds for similarity measures are applied. Detailed studies show that a combination of thresholds...... for the maximum correlation coefficient, the average mutual information, and distancecan reduce the number of blunders in the automated measurements considerably and should therefore be applied. The calculation of DEM errors is carried out by an improved formula. The new methods and procedures are applied to two...

  5. Small catchments DEM creation using Unmanned Aerial Vehicles

    Science.gov (United States)

    Gafurov, A. M.

    2018-01-01

    Digital elevation models (DEM) are an important source of information on the terrain, allowing researchers to evaluate various exogenous processes. The higher the accuracy of DEM the better the level of the work possible. An important source of data for the construction of DEMs are point clouds obtained with terrestrial laser scanning (TLS) and unmanned aerial vehicles (UAV). In this paper, we present the results of constructing a DEM on small catchments using UAVs. Estimation of the UAV DEM showed comparable accuracy with the TLS if real time kinematic Global Positioning System (RTK-GPS) ground control points (GCPs) and check points (CPs) were used. In this case, the main source of errors in the construction of DEMs are the errors in the referencing of survey results.

  6. Design and optimization of the low frequency eddy current technique for the volumetric inspection of austenitic small diameter tubes with a wall thickness up to 12 mm; Auslegung und Optimierung des Niederfrequenz-Wirbelstrom-Verfahrens fuer die volumetrische Pruefung von austenitischen Neben- und Kleinleitungen mit Wandstaerken bis 12 mm

    Energy Technology Data Exchange (ETDEWEB)

    Becker, R.; Bessert, S.; Disque, M.; Weiss, R. [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren, Saarbruecken (Germany)

    1998-11-01

    The low-frequency eddy current technique discussed is a suitable external inspection technique detecting defects at the inner walls of small-diameter tubes and measuring their depths via the ligament. A testing system with optimized sensor lus software for image recording, evaluation, display and documentation is available. The current state of development of the system permits detection and measurement of defects up to 20 mm in size in austenitic inner walls 12.5 mm thick down to a depth of 3 mm. This applies both to the homogenous base metal and the weld with {delta} ferrite. (orig./CB) [Deutsch] Das vorgestellte Niederfrequenz-Wirbelstrom-Verfahren ist geeignet, bei Pruefung von aussen Fehler an der Innenseite von Klein- und Nebenleitungen nachzuweisen und ueber das Ligament deren Tiefe zu bestimmen. Ein entsprechendes Pruefsystem mit optimiertem Sensor und der Software zur Aufnahme, Auswertung, Darstellung und Dokumentation der Wirbelstrom-Urdaten steht zur Verfuegung. Beim jetzigen Entwicklungsstand liegt die Nachweisgrenze fuer einen 20 mm langen Innenfehler in einer 12.5 mm dicken austenitischen Wandung bei einer Fehlertiefe von 3 mm. Dies gilt sowohl fuer den homogenen Grundwerkstoff als auch fuer Schweissgefuege mit {delta}-Ferrit. (orig./MM)

  7. DEM time series of an agricultural watershed

    Science.gov (United States)

    Pineux, Nathalie; Lisein, Jonathan; Swerts, Gilles; Degré, Aurore

    2014-05-01

    In agricultural landscape soil surface evolves notably due to erosion and deposition phenomenon. Even if most of the field data come from plot scale studies, the watershed scale seems to be more appropriate to understand them. Currently, small unmanned aircraft systems and images treatments are improving. In this way, 3D models are built from multiple covering shots. When techniques for large areas would be to expensive for a watershed level study or techniques for small areas would be too time consumer, the unmanned aerial system seems to be a promising solution to quantify the erosion and deposition patterns. The increasing technical improvements in this growth field allow us to obtain a really good quality of data and a very high spatial resolution with a high Z accuracy. In the center of Belgium, we equipped an agricultural watershed of 124 ha. For three years (2011-2013), we have been monitoring weather (including rainfall erosivity using a spectropluviograph), discharge at three different locations, sediment in runoff water, and watershed microtopography through unmanned airborne imagery (Gatewing X100). We also collected all available historical data to try to capture the "long-term" changes in watershed morphology during the last decades: old topography maps, soil historical descriptions, etc. An erosion model (LANDSOIL) is also used to assess the evolution of the relief. Short-term evolution of the surface are now observed through flights done at 200m height. The pictures are taken with a side overlap equal to 80%. To precisely georeference the DEM produced, ground control points are placed on the study site and surveyed using a Leica GPS1200 (accuracy of 1cm for x and y coordinates and 1.5cm for the z coordinate). Flights are done each year in December to have an as bare as possible ground surface. Specific treatments are developed to counteract vegetation effect because it is know as key sources of error in the DEM produced by small unmanned aircraft

  8. evaluating the effects of generalisation approaches and dem ...

    African Journals Online (AJOL)

    Jon

    Digital elevation model (DEM) data are elemental in deriving primary topographic attributes which serve as input variables to a .... This regional study therefore builds on the scientific incentive to further assess the utility of applying DEMs from varying ... The mono-cultured Eucalyptus dominated plantation is owned and ...

  9. Impacts of DEM resolution and area threshold value uncertainty on ...

    African Journals Online (AJOL)

    ... that DEM resolution influences the selected flow accumulation threshold value; the suitable flow accumulation threshold value increases as the DEM resolution increases, and shows greater variability for basins with lower drainage densities. The link between drainage area threshold value and stream network extraction ...

  10. High-resolution DEM Effects on Geophysical Flow Models

    Science.gov (United States)

    Williams, M. R.; Bursik, M. I.; Stefanescu, R. E. R.; Patra, A. K.

    2014-12-01

    Geophysical mass flow models are numerical models that approximate pyroclastic flow events and can be used to assess the volcanic hazards certain areas may face. One such model, TITAN2D, approximates granular-flow physics based on a depth-averaged analytical model using inputs of basal and internal friction, material volume at a coordinate point, and a GIS in the form of a digital elevation model (DEM). The volume of modeled material propagates over the DEM in a way that is governed by the slope and curvature of the DEM surface and the basal and internal friction angles. Results from TITAN2D are highly dependent upon the inputs to the model. Here we focus on a single input: the DEM, which can vary in resolution. High resolution DEMs are advantageous in that they contain more surface details than lower-resolution models, presumably allowing modeled flows to propagate in a way more true to the real surface. However, very high resolution DEMs can create undesirable artifacts in the slope and curvature that corrupt flow calculations. With high-resolution DEMs becoming more widely available and preferable for use, determining the point at which high resolution data is less advantageous compared to lower resolution data becomes important. We find that in cases of high resolution, integer-valued DEMs, very high-resolution is detrimental to good model outputs when moderate-to-low (solutions for rectification of the problem.

  11. Evaluating the effects of generalisation approaches and DEM ...

    African Journals Online (AJOL)

    Digital elevation model (DEM) data are elemental in deriving primary topographic attributes which serve as input variables to a variety of hydrologic and geomorphologic studies. There is however still varied consensus on the effect of DEM source and resolution on the application of these topographic attributes to landscape ...

  12. Huldrich Zwingli se Von dem Touff, vom Widertouff und vom ...

    African Journals Online (AJOL)

    Huldrich Zwingli's 'Von dem Touff, vom Widertouff und vom Kindertouff': Some aspects of Zwringli's theological thought. The aim of this article is to let Zwingli speak for himself as he expresses himself in his treatise on baptism; Von dem Touff, vom Widertouff und vom Kindertouff. The use of secondary literature is avoided in ...

  13. Evaluating the influence of spatial resolutions of DEM on watershed ...

    Indian Academy of Sciences (India)

    Digital elevation model (DEM) of a watershed forms key basis for hydrologic modelling and its resolution plays a key role in accurate prediction of various hydrological processes. This study appraises the effect of different DEMs with varied spatial resolutions (namely TOPO 20 m, CARTO 30 m, ASTER 30 m, SRTM 90 m, ...

  14. Analysis of Users and Uses of DEMs in Spain

    Directory of Open Access Journals (Sweden)

    José Luis Mesa-Mingorance

    2017-12-01

    Full Text Available We have carried out a characterization of users and uses of Digital Elevation Models (DEMs, in order to be able to study an adaptation of the most appropriate DEM. In the previous literature, there have not been many similar studies of this subject. We used information about DEMs downloaded from a Download Center of a National Mapping Service (in this case the Centro Nacional de Información Geográfica, CNIG, of Spain. This service offers three DEM products with different spatial resolutions (DEM05, DEM25 and DEM200. We employed a total of 12,493 records from an online survey. The completion of the survey was mandatory at the time of the download (year 2014. We determined the geographical location of downloads, the profile of users, the use of the DEMs and the user assessment. We identified 6087 different users, most with a profile of private professionals (71% and related educational activities (18%. Most of the users performed only one download. The major uses are those related to teaching-research and professional activities. Uses related to leisure, sport and tourism were 9.5% of all cases. The valuation performed by users of the utility of the products was very high, but not particularly in relation to updating needs.

  15. BlazeDEM3D-GPU A Large Scale DEM simulation code for GPUs

    Directory of Open Access Journals (Sweden)

    Govender Nicolin

    2017-01-01

    Full Text Available Accurately predicting the dynamics of particulate materials is of importance to numerous scientific and industrial areas with applications ranging across particle scales from powder flow to ore crushing. Computational discrete element simulations is a viable option to aid in the understanding of particulate dynamics and design of devices such as mixers, silos and ball mills, as laboratory scale tests comes at a significant cost. However, the computational time required to simulate an industrial scale simulation which consists of tens of millions of particles can take months to complete on large CPU clusters, making the Discrete Element Method (DEM unfeasible for industrial applications. Simulations are therefore typically restricted to tens of thousands of particles with highly detailed particle shapes or a few million of particles with often oversimplified particle shapes. However, a number of applications require accurate representation of the particle shape to capture the macroscopic behaviour of the particulate system. In this paper we give an overview of the recent extensions to the open source GPU based DEM code, BlazeDEM3D-GPU, that can simulate millions of polyhedra and tens of millions of spheres on a desktop computer with a single or multiple GPUs.

  16. BlazeDEM3D-GPU A Large Scale DEM simulation code for GPUs

    Science.gov (United States)

    Govender, Nicolin; Wilke, Daniel; Pizette, Patrick; Khinast, Johannes

    2017-06-01

    Accurately predicting the dynamics of particulate materials is of importance to numerous scientific and industrial areas with applications ranging across particle scales from powder flow to ore crushing. Computational discrete element simulations is a viable option to aid in the understanding of particulate dynamics and design of devices such as mixers, silos and ball mills, as laboratory scale tests comes at a significant cost. However, the computational time required to simulate an industrial scale simulation which consists of tens of millions of particles can take months to complete on large CPU clusters, making the Discrete Element Method (DEM) unfeasible for industrial applications. Simulations are therefore typically restricted to tens of thousands of particles with highly detailed particle shapes or a few million of particles with often oversimplified particle shapes. However, a number of applications require accurate representation of the particle shape to capture the macroscopic behaviour of the particulate system. In this paper we give an overview of the recent extensions to the open source GPU based DEM code, BlazeDEM3D-GPU, that can simulate millions of polyhedra and tens of millions of spheres on a desktop computer with a single or multiple GPUs.

  17. Acidente vascular cerebral e demência vascular no idoso

    OpenAIRE

    Ionel, Cristina

    2015-01-01

    Trabalho final de mestrado integrado em Medicina, apresentado à Faculdade de Medicina da Universidade de Coimbra. Em consequência de um fenómeno global de envelhecimento populacional, é expectável um aumento na prevalência de demência. A demência vascular é a segunda causa mais comum de demência, depois da doença de Alzheimer. Trata-se de uma entidade clínica bastante heterogénea, sendo o acidente vascular cerebral (AVC) um dos seus mecanismos subjacentes. No entanto, nem todos os doentes ...

  18. Hydraulic fracturing - an attempt of DEM simulation

    Science.gov (United States)

    Kosmala, Alicja; Foltyn, Natalia; Klejment, Piotr; Dębski, Wojciech

    2017-04-01

    Hydraulic fracturing is a technique widely used in oil, gas and unconventional reservoirs exploitation in order to enable the oil/gas to flow more easily and enhance the production. It relays on pumping into a rock a special fluid under a high pressure which creates a set of microcracks which enhance porosity of the reservoir rock. In this research, attempt of simulation of such hydrofracturing process using the Discrete Element Method approach is presented. The basic assumption of this approach is that the rock can be represented as an assembly of discrete particles cemented into a rigid sample (Potyondy 2004). An existence of voids among particles simulates then a pore system which can be filled out by fracturing fluid, numerically represented by much smaller particles. Following this microscopic point of view and its numerical representation by DEM method we present primary results of numerical analysis of hydrofracturing phenomena, using the ESyS-Particle Software. In particular, we consider what is happening in distinct vicinity of the border between rock sample and fracking particles, how cracks are creating and evolving by breaking bonds between particles, how acoustic/seismic energy is releasing and so on. D.O. Potyondy, P.A. Cundall. A bonded-particle model for rock. International Journal of Rock Mechanics and Mining Sciences, 41 (2004), pp. 1329-1364.

  19. Digital Elevation Models (DEMs) for the main 8 Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digital elevation model (DEM) data are arrays of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM) projection...

  20. VT USGS NED Hydro-flattened DEM (30 meter) - statewide

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) VTHYDRODEM was created to produce a "hydrologically correct" DEM, compliant with the Vermont Hydrography Dataset (VHD) in support of the "flow...

  1. 2015 USACE NCMP Topobathy Lidar DEM: Avalon (NJ)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These Digital Elevation Model (DEM) files contain rasterized topobathy lidar elevations at a 1 m grid size, generated from data collected by the Coastal Zone Mapping...

  2. 2016 USACE NCMP Topobathy Lidar DEM: Gulf Coast (TX)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These bare earth Digital Elevation Model (DEM) files contain rasterized topobathy lidar elevations at a 1 meter grid size, generated from data collected by the...

  3. 2015 USACE NCMP Topobathy Lidar DEM: Egmont Key (FL)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These 1 m gridded bare earth Digital Elevation Model (DEM) files contain rasterized topobathy lidar elevations generated from data collected by the Coastal Zone...

  4. IceBridge DMS L3 Photogrammetric DEM

    Data.gov (United States)

    National Aeronautics and Space Administration — The IceBridge DMS L3 Photogrammetric DEM (IODMS3) data set contains gridded digital elevation models and orthorectified images of Greenland derived from the Digital...

  5. VT Lidar Hydro-flattened DEM (2 meter) - 2012 - Bennington

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Bennington County 2012 2.0m and Digital Elevation Model (DEM) datasets of various...

  6. 2013 USACE NCMP Topobathy Lidar DEM: Niihau (HI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These Digital Elevation Model (DEM) files contain rasterized topobathy lidar elevations at a 1 m grid size, generated from data collected by the Coastal Zone Mapping...

  7. 2015 USACE NCMP Topobathy Lidar DEM: Sand Island (WA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These Digital Elevation Model (DEM) files contain rasterized topobathy lidar elevations at a 1 m grid size, generated from data collected by the Coastal Zone Mapping...

  8. Greenland 5 km DEM, Ice Thickness, and Bedrock Elevation Grids

    Data.gov (United States)

    National Aeronautics and Space Administration — A Digital Elevation Model (DEM), ice thickness grid, and bedrock elevation grid of Greenland acquired as part of the PARCA program are available in ASCII text format...

  9. DEM Uncertainty propagation in second derivatives geomorphometrical maps

    Science.gov (United States)

    Cosmin Sandric, Ionut; Ursaru, Petre

    2013-04-01

    In order to model the uncertainty from DEM a special model was created and implemented as Python script in ArcGIS Desktop using the ArcPy SDK provided by ESRI. The model is based on Monte Carlo simulation for generating noise and Map Algebra for adding the noise to DEM. The model can be used and independent script or combined with any other models. The inputs of the model are a DEM and an estimation of the DEM accuracy expressed as mean and standard deviation of the errors. The mean and standard deviation may be obtained from a crossvalidation/validation operation, if the model is obtained with geostatistics or by a simple validation with ground control points, if the model is obtained by other means than geostatistics. The DEM uncertainty propagation model assumes that the errors are normally distributed and thus the noise is normal distributed. This version of the model requires a Spatial Analyst extension, but the future versions may be used without or with Spatial Analyst extension. The main issue related with the addition of noise to DEM's in order to compensate for uncertainty is that the second derivatives are almost impossible to extract. This drawback was overcome by using and interpolated noisy surface in the uncertainty propagation model. Statistical analysis on raster obtained in each Monte Carlo simulation; for each realization of the model the following statistical analysis are performed: mean, minimum, maximum, range and standard deviation are extracted and saved as ESRI GRID format When the model finishes the specialist have an image about the uncertainties that might be contained by the DEM and in the same time have a collection of DEM that can be used to generate first and second order derivatives

  10. Enhanced ASTER DEMs for Decadal Measurements of Glacier Elevation Changes

    Science.gov (United States)

    Girod, L.; Nuth, C.; Kääb, A.

    2016-12-01

    Elevation change data is critical to the understanding of a number of geophysical processes, including glaciers through the measurement their volume change. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) system on-board the Terra (EOS AM-1) satellite has been a unique source of systematic stereoscopic images covering the whole globe at 15m resolution and at a consistent quality for over 15 years. While satellite stereo sensors with significantly improved radiometric and spatial resolution are available today, the potential of ASTER data lies in its long consistent time series that is unrivaled, though not fully exploited for change analysis due to lack of data accuracy and precision. ASTER data are strongly affected by attitude jitter, mainly of approximately 4 and 30 km wavelength, and improving the generation of ASTER DEMs requires removal of this effect. We developed MMASTER, an improved method for ASTER DEM generation and implemented it in the open source photogrammetric library and software suite MicMac. The method relies on the computation of a rational polynomial coefficients (RPC) model and the detection and correction of cross-track sensor jitter in order to compute DEMs. Our sensor modeling does not require ground control points and thus potentially allows for automatic processing of large data volumes. When compared to ground truth data, we have assessed a ±5m accuracy in DEM differencing when using our processing method, improved from the ±30m when using the AST14DMO DEM product. We demonstrate and discuss this improved ASTER DEM quality for a number of glaciers in Greenland (See figure attached), Alaska, and Svalbard. The quality of our measurements promises to further unlock the underused potential of ASTER DEMs for glacier volume change time series on a global scale. The data produced by our method will thus help to better understand the response of glaciers to climate change and their influence on runoff and sea level.

  11. EVALUATING THE ACCURACY OF DEM GENERATION ALGORITHMS FROM UAV IMAGERY

    Directory of Open Access Journals (Sweden)

    J. J. Ruiz

    2013-08-01

    Full Text Available In this work we evaluated how the use of different positioning systems affects the accuracy of Digital Elevation Models (DEMs generated from aerial imagery obtained with Unmanned Aerial Vehicles (UAVs. In this domain, state-of-the-art DEM generation algorithms suffer from typical errors obtained by GPS/INS devices in the position measurements associated with each picture obtained. The deviations from these measurements to real world positions are about meters. The experiments have been carried out using a small quadrotor in the indoor testbed at the Center for Advanced Aerospace Technologies (CATEC. This testbed houses a system that is able to track small markers mounted on the UAV and along the scenario with millimeter precision. This provides very precise position measurements, to which we can add random noise to simulate errors in different GPS receivers. The results showed that final DEM accuracy clearly depends on the positioning information.

  12. Evaluating the Accuracy of dem Generation Algorithms from Uav Imagery

    Science.gov (United States)

    Ruiz, J. J.; Diaz-Mas, L.; Perez, F.; Viguria, A.

    2013-08-01

    In this work we evaluated how the use of different positioning systems affects the accuracy of Digital Elevation Models (DEMs) generated from aerial imagery obtained with Unmanned Aerial Vehicles (UAVs). In this domain, state-of-the-art DEM generation algorithms suffer from typical errors obtained by GPS/INS devices in the position measurements associated with each picture obtained. The deviations from these measurements to real world positions are about meters. The experiments have been carried out using a small quadrotor in the indoor testbed at the Center for Advanced Aerospace Technologies (CATEC). This testbed houses a system that is able to track small markers mounted on the UAV and along the scenario with millimeter precision. This provides very precise position measurements, to which we can add random noise to simulate errors in different GPS receivers. The results showed that final DEM accuracy clearly depends on the positioning information.

  13. Discrete Element Modeling (DEM) of Triboelectrically Charged Particles: Revised Experiments

    Science.gov (United States)

    Hogue, Michael D.; Calle, Carlos I.; Curry, D. R.; Weitzman, P. S.

    2008-01-01

    In a previous work, the addition of basic screened Coulombic electrostatic forces to an existing commercial discrete element modeling (DEM) software was reported. Triboelectric experiments were performed to charge glass spheres rolling on inclined planes of various materials. Charge generation constants and the Q/m ratios for the test materials were calculated from the experimental data and compared to the simulation output of the DEM software. In this paper, we will discuss new values of the charge generation constants calculated from improved experimental procedures and data. Also, planned work to include dielectrophoretic, Van der Waals forces, and advanced mechanical forces into the software will be discussed.

  14. Großbritannien auf dem Weg zum Euro?

    OpenAIRE

    Horn, Gustav A.; Volz, Joachim

    2002-01-01

    Mit dem Ausscheren aus dem Wechselkurssystem des Europäischen Währungssystems (EWS) im Jahre 1992 und der sich anschließenden Abwertung des Pfund Sterling um 20 % ist Großbritannien einen eigenen Weg bei der Integration in den europäischen Markt gegangen. Nicht zuletzt aus grundsätzlichen Bedenken, die sich aus der Beschränkung der parlamentarischen Budgethoheit durch den Vertrag von Maastricht ergaben, beteiligte sich das Vereinigte Königreich nicht am Konvergenzprozess zur Währungsunion. Ök...

  15. Geodetic mass balance of the Patagonian Icefields from STRM and TanDEM-X DEMs

    Science.gov (United States)

    Abdel Jaber, W.; Floricioiu, D.; Rott, H.

    2016-12-01

    The Northern and Southern Patagonian Icefields (NPI & SPI), represent the largest mid-latitude ice masses in the Southern Hemisphere. They are mostly drained by outlet glaciers with fronts calving into fresh water lakes or Pacific fjords. Both icefields were affected by significant downwasting in the last decades, as confirmed by published mass change trends obtained by means of gravimetric measurements and geodetic methods. Given their unique characteristics and the significant contribution to sea level rise per unit of area, they represent a fundamental barometer for climate research. The Shuttle Radar Topography Mission (SRTM) of 2000 provided the most complete and accurate Digital Elevation Model (DEM) at the time covering the entire globe from 56°S to 60°N. The present TanDEM-X mission shares the same objective aiming at a global coverage with much higher resolution and accuracy. Their combination leads to a unique multitemporal elevation dataset based solely on SAR single pass bistatic interferometry characterized by 11 to 16 year time span: an ideal setup for monitoring long-term large-scale geophysical phenomena. Using this dataset, detailed and extensive ice elevation change maps were obtained for the 12900 km² SPI for the observation period 2000 - 2011/2012 and for the 3900 km² NPI for the period 2000 - 2014. These maps were used to compute the glacier mass balance of the icefields through the geodetic method. Particular emphasis was set on the estimation of the uncertainty of the geodetic mass balance by quantifying all relevant sources of error. Among these, signal penetration into dry ice and snow can affect considerably radar elevation measurements. For this purpose the backscattering coefficient of the acquisitions along with concurrent meteorological data were analyzed to assess the conditions of the icefield surface. Mass change rates of -3.96±0.14 Gt a-1 and of -13.14±0.42 Gt a-1 (excluding subaqueous loss) were obtained for NPI and SPI

  16. Evaluating Conveyance-Based DEM Correction Technique on NED and SRTM DEMs for Flood Impact Assessment of the 2010 Cumberland River Flood

    Directory of Open Access Journals (Sweden)

    Md. N. M. Bhuyian

    2017-12-01

    Full Text Available This study assessed the uncertainty in flood impact assessment (FIA that may be introduced by errors in moderate resolution regional and moderate resolution global Digital Elevation Models (DEM. One arc-second National Elevation Dataset (NED and one arc-second Shuttle Radar Topography Mission (SRTM DEMs were selected to represent moderate resolution regional and global DEMs. The relative performance for scenarios based on each of the DEMs was compared to a “control” terrain (combination of surveyed river bathymetry and a 1/3 arc-second LiDAR for floodplains-based scenario. Furthermore, a conveyance-based DEM correction technique was applied to the DEMs for investigating the suitability of the technique on selected DEMs, and determining subsequent improvement in the FIA. The May 2010 flood on the Cumberland River near Nashville, TN, was selected as the case study. It was found that the hydraulic properties necessary to implement the selected DEM correction technique could be more readily estimated from NED compared to SRTM. However, this study also prescribed alternate methods to extract necessary hydraulic properties if the DEM quality was compromised. NED-based hydrodynamic modeling resulted in a high overestimation of the simulated flood stage, but the SRTM-based model was unable to produce any reasonable result prior to DEM correction. Nevertheless, after DEM correction, both models became stable and produced less error. Error in simulated flood consequence (i.e., total structures affected and total loss in dollars also dropped accordingly, following the DEM correction. Therefore, application of this conveyance-based correction technique is reasonably effective on both moderate-resolution regional and global DEMs. The effectiveness of the technique on moderate resolution global DEM underscores the potential for users of remote and data-poor areas.

  17. Removing non-ground points from automated photo-based DEM and evaluation of its accuracy with LiDAR DEM

    Science.gov (United States)

    Dehvari, Abdolhamid; Heck, Richard John

    2012-06-01

    Three sets of DEM, including LiDAR, stereo photo based DEM, and contour-based DEM, were created using different tools and sources. Because different tools produce different raster data sets, they were reprojected into the same coordinate system and converted to point clouds as vector format, then a triangulated irregular network (TIN) retaining all grid or mass points was created from each point coverage. Corresponding orthophoto involved in extracting stereo photo DEM, classified by object-oriented approach to create vector polygons representing non-ground points (building and vegetation classes) and bare-ground elevation points. Non-ground points were removed from stereo pairs DEM using classified orthophoto polygons, and filled with contour DEM data. Also a 5th order trend surface over photo-based DEM was fitted and non-ground points were removed and filled using local interpolation. It was observed that automated photo-based extraction yields high precision terrain models in a short time, reducing manual editing; their accuracy is strictly related to image quality and terrain features. Results showed that such photogrammetric extracted DEM represents better accuracy along x and y directions than LiDAR does, while LiDAR has the best vertical accuracy, compared to other DEMs. The differences between horizontal errors are large since there were no significant differences between vertical errors of LiDAR and photo-based DEM. This indicates that there is a good correlation between elevation points of DEMs, and a stereo pair-based DEM can be a good substitute, whenever LiDAR is not affordable. This study provides several important insights into the magnitudes and spatial patterns of LiDAR and photo-based DEM errors, further studies need to verify the error extent in more diverse landscape. However, automated photo-based DEM extraction is currently an efficient method for collecting data useful for rural and small study area.

  18. Precise baseline determination for the TanDEM-X mission

    Science.gov (United States)

    Koenig, Rolf; Moon, Yongjin; Neumayer, Hans; Wermuth, Martin; Montenbruck, Oliver; Jäggi, Adrian

    The TanDEM-X mission will strive for generating a global precise Digital Elevation Model (DEM) by way of bi-static SAR in a close formation of the TerraSAR-X satellite, already launched on June 15, 2007, and the TanDEM-X satellite to be launched in May 2010. Both satellites carry the Tracking, Occultation and Ranging (TOR) payload supplied by the GFZ German Research Centre for Geosciences. The TOR consists of a high-precision dual-frequency GPS receiver, called Integrated GPS Occultation Receiver (IGOR), and a Laser retro-reflector (LRR) for precise orbit determination (POD) and atmospheric sounding. The IGOR is of vital importance for the TanDEM-X mission objectives as the millimeter level determination of the baseline or distance between the two spacecrafts is needed to derive meter level accurate DEMs. Within the TanDEM-X ground segment GFZ is responsible for the operational provision of precise baselines. For this GFZ uses two software chains, first its Earth Parameter and Orbit System (EPOS) software and second the BERNESE software, for backup purposes and quality control. In a concerted effort also the German Aerospace Center (DLR) generates precise baselines independently with a dedicated Kalman filter approach realized in its FRNS software. By the example of GRACE the generation of baselines with millimeter accuracy from on-board GPS data can be validated directly by way of comparing them to the intersatellite K-band range measurements. The K-band ranges are accurate down to the micrometer-level and therefore may be considered as truth. Both TanDEM-X baseline providers are able to generate GRACE baselines with sub-millimeter accuracy. By merging the independent baselines by GFZ and DLR, the accuracy can even be increased. The K-band validation however covers solely the along-track component as the K-band data measure just the distance between the two GRACE satellites. In addition they inhibit an un-known bias which must be modelled in the comparison, so the

  19. Packing of non-spherical aggregate particles by DEM

    NARCIS (Netherlands)

    Stroeven, P.; He, H.

    2013-01-01

    Loose random and dense random mono-size paclDEM) for eight types of polyhedral grains, for ellipses with different aspect ratio, for cubes and for spheres. Focus was on density, sphericity of the grains and average value and frequency

  20. Spatial Characterization of Landscapes through Multifractal Analysis of DEM

    Directory of Open Access Journals (Sweden)

    P. L. Aguado

    2014-01-01

    Full Text Available Landscape evolution is driven by abiotic, biotic, and anthropic factors. The interactions among these factors and their influence at different scales create a complex dynamic. Landscapes have been shown to exhibit numerous scaling laws, from Horton’s laws to more sophisticated scaling of heights in topography and river network topology. This scaling and multiscaling analysis has the potential to characterise the landscape in terms of the statistical signature of the measure selected. The study zone is a matrix obtained from a digital elevation model (DEM (map 10 × 10 m, and height 1 m that corresponds to homogeneous region with respect to soil characteristics and climatology known as “Monte El Pardo” although the water level of a reservoir and the topography play a main role on its organization and evolution. We have investigated whether the multifractal analysis of a DEM shows common features that can be used to reveal the underlying patterns and information associated with the landscape of the DEM mapping and studied the influence of the water level of the reservoir on the applied analysis. The results show that the use of the multifractal approach with mean absolute gradient data is a useful tool for analysing the topography represented by the DEM.

  1. Evaluating the influence of spatial resolutions of DEM on watershed ...

    Indian Academy of Sciences (India)

    Application of effective models in hydrological studies is vital to understand the natural pro- cesses occurring at .... 200, 300, 500 and 1000 m) on the uncertainties of. SWAT-predicted runoff, sediment, nitrate nitrogen ... lyzing the uncertainties of SWAT outputs due to. DEM resolution on annual and monthly basis (Lin et al.

  2. Erdbeben, Hangrutschungen, Tsunamis und andere Gefahren aus dem Meer

    OpenAIRE

    Krastel, Sebastian

    2009-01-01

    Mit dem Meer verbindet man Schönes und Nützliches wie Badeurlaub oder Fischfang. Es drohen aber auch Gefahren durch Erdbeben oder Tsunamis. Welche Risiken für die Menschheit in den Ozeanen lauern und ob auch Schleswig-Holstein bedroht ist, erklärt Professor Sebastian Krastel.

  3. Artificial terraced field extraction based on high resolution DEMs

    Science.gov (United States)

    Na, Jiaming; Yang, Xin; Xiong, Liyang; Tang, Guoan

    2017-04-01

    With the increase of human activities, artificial landforms become one of the main terrain features with special geographical and hydrological value. Terraced field, as the most important artificial landscapes of the loess plateau, plays an important role in conserving soil and water. With the development of digital terrain analysis (DTA), there is a current and future need in developing a robust, repeatable and cost-effective research methodology for terraced fields. In this paper, a novel method using bidirectional DEM shaded relief is proposed for terraced field identification based on high resolution DEM, taking Zhifanggou watershed, Shannxi province as the study area. Firstly, 1m DEM is obtained by low altitude aerial photogrammetry using Unmanned Aerial Vehicle (UAV), and 0.1m DOM is also obtained as the test data. Then, the positive and negative terrain segmentation is done to acquire the area of terraced field. Finally, a bidirectional DEM shaded relief is simulated to extract the ridges of each terraced field stages. The method in this paper can get not only polygon feature of the terraced field areas but also line feature of terraced field ridges. The accuracy is 89.7% compared with the artificial interpretation result from DOM. And additional experiment shows that this method has a strong robustness as well as high accuracy.

  4. Evaluating DEM results with FEM perspectives of load : soil interaction

    NARCIS (Netherlands)

    Tadesse, D.

    2004-01-01

    Keywords: Load - soil interaction, soil structure, soil mechanical properties, FEM (Finite Element Method), Plaxis (Finite Element Code), granular particles, shear stress, DEM (Distinct Element Method),

  5. Evaluating the influence of spatial resolutions of DEM on watershed ...

    Indian Academy of Sciences (India)

    Digital elevation model (DEM) of a watershed forms key basis for hydrologic modelling and its resolution plays a key role in accurate prediction of ... ies also investigated the effect of spatial resolution of input datasets on hydrological ... watersheds under different management practices. (Arnold et al. 1998). In the past ...

  6. Improved Fluvial Geomorphic Interpretation Derived From DEM Differencing

    Science.gov (United States)

    Wheaton, J. M.; Brasington, J.; Brewer, P. A.; Darby, S.; Pasternack, G. B.; Sear, D.; Vericat, D.; Williams, R.

    2007-12-01

    Technological advances over the past two decades in remotely-sensed and ground-based topographic surveying technologies have made the rapid acquisition of topographic data in the fluvial environment possible at spatial resolutions and extents previously unimaginable. Consequently, monitoring geomorphic changes and estimating fluvial sediment budgets through comparing repeat topographic surveys (DEM differencing) has now become a tractable, affordable approach for both research purposes and long-term monitoring associated with river restoration. However, meaningful quantitative geomorphic interpretation of repeat topographic surveys has received little attention from either researchers or practitioners. Previous research has shown that quantitative estimates of erosion and deposition from DEM differencing are highly sensitive to DEM uncertainty, with minimum level of detection techniques typically discarding between 40% and 90% of the predicted changes. A series of new methods for segregating reach-scale sediment budgets into their specific process components, while accounting for the influence of DEM uncertainty, were developed and explored to highlight distinctive geomorphic signatures between different styles of change. To illustrate the interpretive power of the techniques in different settings, results are presented from analyses across a range of gravel-bed river types: a) the braided River Feshie, Scotland, UK; b) the formerly gravel-mined, wandering Sulphur Creek, California, USA; c) a heavily regulated reach of the Mokelumne River, California, USA that has been subjected to over 5 years of spawning habitat rehabilitation; and d) a restored meandering channel and floodplain of the Highland Water, New Forest, UK. Despite fundamentally different process suites between the study sites, the budget segregation technique is in each case able to aid in more reliable and meaningful geomorphic interpretations of DEM differences.

  7. Hydraulic correction method (HCM) to enhance the efficiency of SRTM DEM in flood modeling

    Science.gov (United States)

    Chen, Huili; Liang, Qiuhua; Liu, Yong; Xie, Shuguang

    2018-04-01

    Digital Elevation Model (DEM) is one of the most important controlling factors determining the simulation accuracy of hydraulic models. However, the currently available global topographic data is confronted with limitations for application in 2-D hydraulic modeling, mainly due to the existence of vegetation bias, random errors and insufficient spatial resolution. A hydraulic correction method (HCM) for the SRTM DEM is proposed in this study to improve modeling accuracy. Firstly, we employ the global vegetation corrected DEM (i.e. Bare-Earth DEM), developed from the SRTM DEM to include both vegetation height and SRTM vegetation signal. Then, a newly released DEM, removing both vegetation bias and random errors (i.e. Multi-Error Removed DEM), is employed to overcome the limitation of height errors. Last, an approach to correct the Multi-Error Removed DEM is presented to account for the insufficiency of spatial resolution, ensuring flow connectivity of the river networks. The approach involves: (a) extracting river networks from the Multi-Error Removed DEM using an automated algorithm in ArcGIS; (b) correcting the location and layout of extracted streams with the aid of Google Earth platform and Remote Sensing imagery; and (c) removing the positive biases of the raised segment in the river networks based on bed slope to generate the hydraulically corrected DEM. The proposed HCM utilizes easily available data and tools to improve the flow connectivity of river networks without manual adjustment. To demonstrate the advantages of HCM, an extreme flood event in Huifa River Basin (China) is simulated on the original DEM, Bare-Earth DEM, Multi-Error removed DEM, and hydraulically corrected DEM using an integrated hydrologic-hydraulic model. A comparative analysis is subsequently performed to assess the simulation accuracy and performance of four different DEMs and favorable results have been obtained on the corrected DEM.

  8. A description of rotations for DEM models of particle systems

    Science.gov (United States)

    Campello, Eduardo M. B.

    2015-06-01

    In this work, we show how a vector parameterization of rotations can be adopted to describe the rotational motion of particles within the framework of the discrete element method (DEM). It is based on the use of a special rotation vector, called Rodrigues rotation vector, and accounts for finite rotations in a fully exact manner. The use of fictitious entities such as quaternions or complicated structures such as Euler angles is thereby circumvented. As an additional advantage, stick-slip friction models with inter-particle rolling motion are made possible in a consistent and elegant way. A few examples are provided to illustrate the applicability of the scheme. We believe that simple vector descriptions of rotations are very useful for DEM models of particle systems.

  9. Generation of Statewide DEMs and Orthoimages – Guidelines and Methodology

    Directory of Open Access Journals (Sweden)

    Giribabu Dandabathula

    2015-06-01

    Full Text Available Cartosat-1 is a global, high resolution stereographic imaging mission to support enhanced applications in several areas of terrain mapping, natural resources management, disaster management, infrastructure and development planning. A collaborative project of generating statewide Digital Elevation Model (DEMs and mosaic of Ortho-image for all the states and union territories in India has completed under the project namely Space based Information Support for Decentralized Planning (SIS-DP using Photogrammetric techniques with Cartosat-1 stereo data.  Approximately 11000 stereo pairs of Cartosat-1 data were used in this process. Photogrammetric blocks for each state were processed using existing reference tiles and accordingly ortho-images were generated. The paper outlines the methodology for generating state-wide Digital Elevation Models (DEMs and ortho-images. The guidelines that govern the quality of the output were discussed. Dissemination mechanism via public accessible web platform was described.

  10. Boreal Forest Biomass Classification with TanDEM-X

    Science.gov (United States)

    Torano Caicoya, Astor; Kugler, Florian; Hajnsek, Irena; Papathanassiou, Kostas

    2013-08-01

    High spatial resolution X-band interferometric SAR data from TanDEM-X acquired in the operational DEM generation mode are sensitive to forest structure and can therefore be used for thematic boreal forest classification. The interferometric coherence in absence of temporal decorrelation depends strongly on forest height and structure. Due to the rather homogenous structure of boreal forest, forest biomass can be derived from forest height, on the basis of allometric equations with sufficient accuracy and can therefore, be used for thematic classification applications. Two test sites in mid- and southern Sweden are investigated. A maximum of 4 biomass classes, up to 150 Mg/ha, for a single baseline scenario and 5 biomass classes up to 250 Mg/ha for a dual baseline scenario, are achieved.

  11. Development of parallel DEM for the open source code MFIX

    Energy Technology Data Exchange (ETDEWEB)

    Gopalakrishnan, Pradeep; Tafti, Danesh

    2013-02-01

    The paper presents the development of a parallel Discrete Element Method (DEM) solver for the open source code, Multiphase Flow with Interphase eXchange (MFIX) based on the domain decomposition method. The performance of the code was evaluated by simulating a bubbling fluidized bed with 2.5 million particles. The DEM solver shows strong scalability up to 256 processors with an efficiency of 81%. Further, to analyze weak scaling, the static height of the fluidized bed was increased to hold 5 and 10 million particles. The results show that global communication cost increases with problem size while the computational cost remains constant. Further, the effects of static bed height on the bubble hydrodynamics and mixing characteristics are analyzed.

  12. Transient Euler-Lagrange/DEM simulation of stent thrombosis

    Directory of Open Access Journals (Sweden)

    Stiehm Michael

    2016-09-01

    Full Text Available Stent implantation is the treatment of choice for cardiovascular diseases. By introduction of biodegradable thick strut stents investigations of thrombosis formation is one focus of research. This study deals with a transient Euler-Lagrange/DEM approach to simulate the flow field, platelet movement and clotting. The recirculation zones prolong particle residence time. As a result, the vicinity of stent struts shown a particularly higher risk for stent thrombosis.

  13. Modeling slow deformation of polygonal particles using DEM

    OpenAIRE

    Pena, Andres A.; Lind, Pedro G.; Herrmann, Hans J.

    2007-01-01

    We introduce two improvements in the numerical scheme to simulate collision and slow shearing of irregular particles. First, we propose an alternative approach based on simple relations to compute the frictional contact forces. The approach improves efficiency and accuracy of the Discrete Element Method (DEM) when modeling the dynamics of the granular packing. We determine the proper upper limit for the integration step in the standard numerical scheme using a wide range of material parameter...

  14. Using DEM-CFD method at colloidal scale

    OpenAIRE

    Chaumeil, Florian

    2013-01-01

    The aim of this work is to look into the applicability of Discrete Element Modelling (DEM) coupled to Computational Fluid Dynamics (CFD) to simulate micro-scale colloidal particles immersed in fluid. Numerical methods were implemented through the commercial framework of EDEM2.3. As opposed to dissolved matter, which behaves as a continuum within the fluid medium, particulate matter is made of discrete entities that interact amongst themselves, and with the fluid and any phys...

  15. Efficient parallel CFD-DEM simulations using OpenMP

    Science.gov (United States)

    Amritkar, Amit; Deb, Surya; Tafti, Danesh

    2014-01-01

    The paper describes parallelization strategies for the Discrete Element Method (DEM) used for simulating dense particulate systems coupled to Computational Fluid Dynamics (CFD). While the field equations of CFD are best parallelized by spatial domain decomposition techniques, the N-body particulate phase is best parallelized over the number of particles. When the two are coupled together, both modes are needed for efficient parallelization. It is shown that under these requirements, OpenMP thread based parallelization has advantages over MPI processes. Two representative examples, fairly typical of dense fluid-particulate systems are investigated, including the validation of the DEM-CFD and thermal-DEM implementation with experiments. Fluidized bed calculations are performed on beds with uniform particle loading, parallelized with MPI and OpenMP. It is shown that as the number of processing cores and the number of particles increase, the communication overhead of building ghost particle lists at processor boundaries dominates time to solution, and OpenMP which does not require this step is about twice as fast as MPI. In rotary kiln heat transfer calculations, which are characterized by spatially non-uniform particle distributions, the low overhead of switching the parallelization mode in OpenMP eliminates the load imbalances, but introduces increased overheads in fetching non-local data. In spite of this, it is shown that OpenMP is between 50-90% faster than MPI.

  16. A simplified DEM numerical simulation of vibroflotation without backfill

    Science.gov (United States)

    Jiang, M. J.; Liu, W. W.; He, J.; Sun, Y.

    2015-09-01

    Vibroflotation is one of the deep vibratory compaction techniques for ground reinforcement. This method densities the soil and improves its mechanical properties, thus helps to protect people's lives and property from geological disasters. The macro reinforcement mechanisms of vibroflotation method have been investigated by numerical simulations, laboratory and in-situ experiments. However, little attention has been paid on its micro - mechanism, which is essential to fully understand the principle of the ground reinforcement. Discrete element method (DEM), based on discrete mechanics, is more powerful to solve large deformation and failure problems. This paper investigated the macro-micro mechanism of vibroflotation without backfill under two conditions, i.e., whether or not the ground water was considered, by incorporating inter-particle rolling resistance model in the DEM simulations. Conclusions obtained are as follows: The DEM simulations incorporating rolling resistance well replicate the mechanical response of the soil assemblages and are in line with practical observations. The void ratio of the granular soil fluctuates up and down in the process of vibroflotation, and finally reduces to a lower value. It is more efficient to densify the ground without water compared to the ground with water.

  17. DEM analysis of FOXSI-2 microflare using AIA observations

    Science.gov (United States)

    Athiray Panchapakesan, Subramania; Glesener, Lindsay; Vievering, Juliana; Camilo Buitrago-Casas, Juan; Christe, Steven; Inglis, Andrew; Krucker, Sam; Musset, Sophie

    2017-08-01

    The second flight of Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment was successfully completed on 11 December 2014. FOXSI makes direct imaging and spectral observation of the Sun in hard X-rays using grazing incidence optics modules which focus X-rays onto seven focal plane detectors kept at a 2m distance, in the energy range 4 to 20 keV, to study particle acceleration and coronal heating. Significant HXR emissions were observed by FOXSI during microflare events with A0.5 and A2.5 class, as classified by GOES, that occurred during FOXSI-2 flight.Spectral analysis of FOXSI data for these events indicate presence of plasma at higher temperatures (>10MK). We attempt to study the plasma content in the corona at different temperatures, characterized by the differential emission measure (DEM), over the FOXSI-2 observed flare regions using the Atmospheric Imaging Assembly (SDO/AIA) data. We utilize AIA observations in different EUV filters that are sensitive to ionized iron lines, to determine the DEM by using a regularized inversion method. This poster will show the properties of hot plasma as derived from FOXSI-2 HXR spectra with supporting DEM analysis using AIA observations.

  18. Validation of DEM prediction for granular avalanches on irregular terrain

    Science.gov (United States)

    Mead, Stuart R.; Cleary, Paul W.

    2015-09-01

    Accurate numerical simulation can provide crucial information useful for a greater understanding of destructive granular mass movements such as rock avalanches, landslides, and pyroclastic flows. It enables more informed and relatively low cost investigation of significant risk factors, mitigation strategy effectiveness, and sensitivity to initial conditions, material, or soil properties. In this paper, a granular avalanche experiment from the literature is reanalyzed and used as a basis to assess the accuracy of discrete element method (DEM) predictions of avalanche flow. Discrete granular approaches such as DEM simulate the motion and collisions of individual particles and are useful for identifying and investigating the controlling processes within an avalanche. Using a superquadric shape representation, DEM simulations were found to accurately reproduce transient and static features of the avalanche. The effect of material properties on the shape of the avalanche deposit was investigated. The simulated avalanche deposits were found to be sensitive to particle shape and friction, with the particle shape causing the sensitivity to friction to vary. The importance of particle shape, coupled with effect on the sensitivity to friction, highlights the importance of quantifying and including particle shape effects in numerical modeling of granular avalanches.

  19. Modelling above Ground Biomass in Tanzanian Miombo Woodlands Using TanDEM-X WorldDEM and Field Data

    Directory of Open Access Journals (Sweden)

    Stefano Puliti

    2017-09-01

    Full Text Available The use of Interferometric Synthetic Aperture Radar (InSAR data has great potential for monitoring large scale forest above ground biomass (AGB in the tropics due to the increased ability to retrieve 3D information even under cloud cover. To date; results in tropical forests have been inconsistent and further knowledge on the accuracy of models linking AGB and InSAR height data is crucial for the development of large scale forest monitoring programs. This study provides an example of the use of TanDEM-X WorldDEM data to model AGB in Tanzanian woodlands. The primary objective was to assess the accuracy of a model linking AGB with InSAR height from WorldDEM after the subtraction of ground heights. The secondary objective was to assess the possibility of obtaining InSAR height for field plots when the terrain heights were derived from global navigation satellite systems (GNSS; i.e., as an alternative to using airborne laser scanning (ALS. The results revealed that the AGB model using InSAR height had a predictive accuracy of R M S E = 24.1 t·ha−1; or 38.8% of the mean AGB when terrain heights were derived from ALS. The results were similar when using terrain heights from GNSS. The accuracy of the predicted AGB was improved when compared to a previous study using TanDEM-X for a sub-area of the area of interest and was of similar magnitude to what was achieved in the same sub-area using ALS data. Overall; this study sheds new light on the opportunities that arise from the use of InSAR data for large scale AGB modelling in tropical woodlands.

  20. Der Meteorologe : (aus dem Band "V". Tallinn 1998) / Elo Viiding ; aus dem Estnischen von Gisbert Jänicke

    Index Scriptorium Estoniae

    Viiding, Elo, 1974-

    2002-01-01

    Sisu : Die Möglichkeit des Meteorologen = Meteoroloogi võimalikkusest ; "Der Meteorologe kam 1990 in die Stadt..." = "Meteoroloog saabus linna aastal 1990..." ; "Was wäre dir "Arbeit" des Meteorologen..." = "Mis oleks meteoroloogi töö..." ; "Und ein Unglück für den Meteorologen ist es auch..." = "Ja Meteoroloogi õnnetus on veel see..." ; Angst vor dem Altwerden des Meteorologen = Hirm Meteoroloogi vanakssaamise ees ; Fest. Geschenk = Pidu. Kink ; "Wenn der Meteorologe eine Grösse sieht, ist er darüber..." = "Kui meteoroloog näeb suurust, on ta selle kohal..." ; Der Meteorologe wird im Saal erwartet = Meteoroloogi oodatakse saali ; "Das Abkommen mit der Meteorologenerwartung kündigen..." = "Katkestada leping meteoroloogiootusega..." ; "Die "Wege des Herrn" sind der Meteorologe..." = "Looja tee" on Meteoroloog..." ; Von dem Fremden, der im Saal den Meteorologen traf = Võõra lugu, kes Meteoroloogi saalis kohtas ; "Den Fremden hervorzuhusten, der von dem..." = "Köhida enesest välja võõras, kes tahtis teha..." ; Der Fremde beruhigt sich nicht = Võõras ei jää rahule

  1. [Julia Rosche. Zwischen den Fronten. Die Rolle Estlands zwischen dem Hitler-Stalin-Pakt und dem Ende des Zweiten Weltkriegs im internationalen Kontext] / Olaf Mertelsmann

    Index Scriptorium Estoniae

    Mertelsmann, Olaf, 1969-

    2014-01-01

    Arvustus: Rosche, Julia. Zwischen den Fronten. Die Rolle Estlands zwischen dem Hitler-Stalin-Pakt und dem Ende des Zweiten Weltkriegs im internationalen Kontext. Diplomica Verlag. Hamburg 2012. Unter demselben Titel mit identischem Text auch: Grin Verlag. München 2013

  2. Wavelet based analysis of TanDEM-X and LiDAR DEMs across a tropical vegetation heterogeneity gradient driven by fire disturbance in Indonesia

    NARCIS (Netherlands)

    Grandi, De Elsa Carla; Mitchard, Edward; Hoekman, Dirk

    2016-01-01

    Three-dimensional information provided by TanDEM-X interferometric phase and airborne Light Detection and Ranging (LiDAR) Digital ElevationModels (DEMs) were used to detect differences in vegetation heterogeneity through a disturbance gradient in Indonesia. The range of vegetation types developed

  3. Research on the method of extracting DEM based on GBInSAR

    Science.gov (United States)

    Yue, Jianping; Yue, Shun; Qiu, Zhiwei; Wang, Xueqin; Guo, Leping

    2016-05-01

    Precise topographical information has a very important role in geology, hydrology, natural resources survey and deformation monitoring. The extracting DEM technology based on synthetic aperture radar interferometry (InSAR) obtains the three-dimensional elevation of the target area through the phase information of the radar image data. The technology has large-scale, high-precision, all-weather features. By changing track in the location of the ground radar system up and down, it can form spatial baseline. Then we can achieve the DEM of the target area by acquiring image data from different angles. Three-dimensional laser scanning technology can quickly, efficiently and accurately obtain DEM of target area, which can verify the accuracy of DEM extracted by GBInSAR. But research on GBInSAR in extracting DEM of the target area is a little. For lack of theory and lower accuracy problems in extracting DEM based on GBInSAR now, this article conducted research and analysis on its principle deeply. The article extracted the DEM of the target area, combined with GBInSAR data. Then it compared the DEM obtained by GBInSAR with the DEM obtained by three-dimensional laser scan data and made statistical analysis and normal distribution test. The results showed the DEM obtained by GBInSAR was broadly consistent with the DEM obtained by three-dimensional laser scanning. And its accuracy is high. The difference of both DEM approximately obeys normal distribution. It indicated that extracting the DEM of target area based on GBInSAR is feasible and provided the foundation for the promotion and application of GBInSAR.

  4. Determination of input data for numerical design of sheet steels - report on a common research project of the steel and automotive industry; Ermittlung von Berechnungskennwerten an Karosseriewerkstoffen - Bericht ueber ein gemeinschaftsprojekt der Stahl- und Automobilindustrie

    Energy Technology Data Exchange (ETDEWEB)

    Bleck, W.; Frehn, A. [Institut fuer Eisenhuettenkunde, RWTH Aachen (Germany); Engl, B. [ThyssenKrupp Stahl AG, Dortmund (Germany); Nicklas, D. [Saint-Gobain Sekurit Deutschland GmbH and Co KG, Aachen (Germany); Steinbeck, G. [Stahlinstitut VDEh, Duesseldorf (Germany)

    2004-08-01

    Within the scope of a common research project of the steel and automotive industry, 20 sheet steels have been investigated to obtain input data for FE-analysis. In detail, elastic, plastic and fatique characteristical values were determined by several testing institutes for a period of 3 years. The investigated sheet steels differ with regard to the microstructure and the steel concept. Beside several ferritic steels, multiphase steels like dual phase-, complex phase- and TRIP steels as well as 2 austenitic stainless steels were characterised. The starting materials and selected steels with a defined predeformation and heat treatment were investigated. Within this project, the partners developed a testing and documentation precept in which the ways and means were fixed to reach the defined steel condition and to enable a standardised testing and data output for the material database, realised by the automotive industry. Before the actual elastic, plastic and fatique testing, a reception test for all steels was carried out to characterise the materials with regard to the microstructure, surface condition, chemical composition and mechanical properties, obtained in the quasistatic tensile test. The results of the different testing institutes (elastic, plastic and fatique) will be presented in separate publications in detail. As a result of this project it became obvious that the investigated steels can be divided into steel groups which show a similar strain hardening behaviour. Thus, a prediction of mechanical values and flow curves for cognate steels within one steel group seems to be possible. This subject will be the focus of further investigations within the scope of a new project started on January 1{sup st}, 2003. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Im Rahmen eines gemeinschaftlichen Projektes der Stahl- und Automobilindustrie wurden an insgesamt 20 Staehlen fuer Feinblech Kennwerte fuer die FEM-Simulation ermittelt. Im Einzelnen

  5. 3D DEM analyses of the 1963 Vajont rock slide

    Science.gov (United States)

    Boon, Chia Weng; Houlsby, Guy; Utili, Stefano

    2013-04-01

    The 1963 Vajont rock slide has been modelled using the distinct element method (DEM). The open-source DEM code, YADE (Kozicki & Donzé, 2008), was used together with the contact detection algorithm proposed by Boon et al. (2012). The critical sliding friction angle at the slide surface was sought using a strength reduction approach. A shear-softening contact model was used to model the shear resistance of the clayey layer at the slide surface. The results suggest that the critical sliding friction angle can be conservative if stability analyses are calculated based on the peak friction angles. The water table was assumed to be horizontal and the pore pressure at the clay layer was assumed to be hydrostatic. The influence of reservoir filling was marginal, increasing the sliding friction angle by only 1.6˚. The results of the DEM calculations were found to be sensitive to the orientations of the bedding planes and cross-joints. Finally, the failure mechanism was investigated and arching was found to be present at the bend of the chair-shaped slope. References Boon C.W., Houlsby G.T., Utili S. (2012). A new algorithm for contact detection between convex polygonal and polyhedral particles in the discrete element method. Computers and Geotechnics, vol 44, 73-82, doi.org/10.1016/j.compgeo.2012.03.012. Kozicki, J., & Donzé, F. V. (2008). A new open-source software developed for numerical simulations using discrete modeling methods. Computer Methods in Applied Mechanics and Engineering, 197(49-50), 4429-4443.

  6. Optimization of Particle Search Algorithm for CFD-DEM Simulations

    Directory of Open Access Journals (Sweden)

    G. Baryshev

    2013-09-01

    Full Text Available Discrete element method has numerous applications in particle physics. However, simulating particles as discrete entities can become costly for large systems. In time-driven DEM simulation most computation time is taken by contact search stage. We propose an efficient collision detection method which is based on sorting particles by their coordinates. Using multiple sorting criteria allows minimizing number of potential neighbours and defines fitness of this approach for simulation of massive systems in 3D. This method is compared to a common approach that consists of placing particles onto a grid of cells. Advantage of the new approach is independence of simulation parameters upon particle radius and domain size.

  7. Comparative DEMS study on the electrochemical oxidation of carbon blacks

    DEFF Research Database (Denmark)

    Ashton, Sean James; Arenz, Matthias

    2012-01-01

    heat-treated between 2100 and 3200 °C, such as those typically used as corrosion resistant carbon (CRC) supports for polymer electrolyte membrane fuel cell (PEMFC) catalysts. A methodology combining cyclic voltammetry (CV) and differential electrochemical mass spectrometry (DEMS) is used, which allows......; however, CRC samples graphitised =2800 °C did not exhibit this same behaviour. Highlights ¿ We quantitatively determine electrooxidation of carbon support materials. ¿ We can distinguish between the total and partial electrooxidation. ¿ Non or mildly heat treated carbon forms passivating layer. ¿ Heat...

  8. A LBM-DEM solver for fast discrete particle simulation of particle-fluid flows

    Science.gov (United States)

    Xiong, Qingang; Madadi-Kandjani, Ehsan; Lorenzini, Giulio

    2014-04-01

    The lattice Boltzmann method (LBM) for simulating fluid phases was coupled with the discrete element method (DEM) for studying solid phases to formulate a novel solver for fast discrete particle simulation (DPS) of particle-fluid flows. The fluid hydrodynamics was obtained by solving LBM equations instead of solving the Navier-Stokes equation by the finite volume method (FVM). Interparticle and particle-wall collisions were determined by DEM. The new DPS solver was validated by simulating a three-dimensional gas-solid bubbling fluidized bed. The new solver was found to yield results faster than its FVM-DEM counterpart, with the increase in the domain-averaged gas volume fraction. Additionally, the scalability of the LBM-DEM DPS solver was superior to that of the FVM-DEM DPS solver in parallel computing. Thus, the LBM-DEM DPS solver is highly suitable for use in simulating dilute and large-scale particle-fluid flows.

  9. Investigation on velocity distribution of TFM and DEM phase in hybrid model of CBFB in mining

    Science.gov (United States)

    Zhang, Tianyu; Feng, Ying; Zhao, Zhening

    2017-05-01

    As a novel model for gas solid flow simulation, the investigation of TFM-DEM hybrid model is far from completely, including mutual interaction of TFM and DEM phase, selection of DEM portion and coherence of the predicted results from both phases. Therefore, in present study, the consistency of velocity distribution between TFM and DEM phase is investigated. The correlation of instantaneous and time-averaged velocity distribution of TFM and DEM phase in specific area in CBFB for mining is studied. And the differences of the axial and radial velocity between the particles of different sizes are discussed. The influence of particle diameter and the ratio of DEM and TFM phase on the correlation of velocity, both instantaneous and time-averaged, are taken into consideration.

  10. The Importance of Precise Digital Elevation Models (DEM) in Modelling Floods

    Science.gov (United States)

    Demir, Gokben; Akyurek, Zuhal

    2016-04-01

    Digital elevation Models (DEM) are important inputs for topography for the accurate modelling of floodplain hydrodynamics. Floodplains have a key role as natural retarding pools which attenuate flood waves and suppress flood peaks. GPS, LIDAR and bathymetric surveys are well known surveying methods to acquire topographic data. It is not only time consuming and expensive to obtain topographic data through surveying but also sometimes impossible for remote areas. In this study it is aimed to present the importance of accurate modelling of topography for flood modelling. The flood modelling for Samsun-Terme in Blacksea region of Turkey is done. One of the DEM is obtained from the point observations retrieved from 1/5000 scaled orthophotos and 1/1000 scaled point elevation data from field surveys at x-sections. The river banks are corrected by using the orthophotos and elevation values. This DEM is named as scaled DEM. The other DEM is obtained from bathymetric surveys. 296 538 number of points and the left/right bank slopes were used to construct the DEM having 1 m spatial resolution and this DEM is named as base DEM. Two DEMs were compared by using 27 x-sections. The maximum difference at thalweg of the river bed is 2m and the minimum difference is 20 cm between two DEMs. The channel conveyance capacity in base DEM is larger than the one in scaled DEM and floodplain is modelled in detail in base DEM. MIKE21 with flexible grid is used in 2- dimensional shallow water flow modelling. The model by using two DEMs were calibrated for a flood event (July 9, 2012). The roughness is considered as the calibration parameter. From comparison of input hydrograph at the upstream of the river and output hydrograph at the downstream of the river, the attenuation is obtained as 91% and 84% for the base DEM and scaled DEM, respectively. The time lag in hydrographs does not show any difference for two DEMs and it is obtained as 3 hours. Maximum flood extents differ for the two DEMs

  11. A seamless, high-resolution digital elevation model (DEM) of the north-central California coast

    Science.gov (United States)

    Foxgrover, Amy C.; Barnard, Patrick L.

    2012-01-01

    A seamless, 2-meter resolution digital elevation model (DEM) of the north-central California coast has been created from the most recent high-resolution bathymetric and topographic datasets available. The DEM extends approximately 150 kilometers along the California coastline, from Half Moon Bay north to Bodega Head. Coverage extends inland to an elevation of +20 meters and offshore to at least the 3 nautical mile limit of state waters. This report describes the procedures of DEM construction, details the input data sources, and provides the DEM for download in both ESRI Arc ASCII and GeoTIFF file formats with accompanying metadata.

  12. DEM Resolution Impact on the Estimation of the Physical Characteristics of Watersheds by Using SWAT

    Directory of Open Access Journals (Sweden)

    Waranyu Buakhao

    2016-01-01

    Full Text Available A digital elevation model (DEM is an important spatial input for automatic extraction of topographic parameters for the soil and water assessment tool (SWAT. The objective of this study was to investigate the impact of DEM resolution (from 5 to 90 m on the delineation process of a SWAT model with two types of watershed characteristics (flat area and mountain area and three sizes of watershed area (about 20,000, 200,000, and 1,500,000 hectares. The results showed that the total lengths of the streamline, main channel slope, watershed area, and area slope were significantly different when using the DEM datasets to delineate. Delineation using the SRTM DEM (90 m, ASTER DEM (30 m, and LDD DEM (5 m for all watershed characteristics showed that the watershed sizes and shapes obtained were only slightly different, whereas the area slopes obtained were significantly different. The total lengths of the generated streams increased when the resolution of the DEM used was higher. The stream slopes obtained using the small area sizes were insignificant, whereas the slopes obtained using the large area sizes were significantly different. This suggests that water resource model users should use the ASTER DEM as opposed to a finer resolution DEM for model input to save time for the model calibration and validation.

  13. Multi-scale sensitivity analysis of pile installation using DEM

    Science.gov (United States)

    Esposito, Ricardo Gurevitz; Velloso, Raquel Quadros; , Eurípedes do Amaral Vargas, Jr.; Danziger, Bernadete Ragoni

    2017-12-01

    The disturbances experienced by the soil due to the pile installation and dynamic soil-structure interaction still present major challenges to foundation engineers. These phenomena exhibit complex behaviors, difficult to measure in physical tests and to reproduce in numerical models. Due to the simplified approach used by the discrete element method (DEM) to simulate large deformations and nonlinear stress-dilatancy behavior of granular soils, the DEM consists of an excellent tool to investigate these processes. This study presents a sensitivity analysis of the effects of introducing a single pile using the PFC2D software developed by Itasca Co. The different scales investigated in these simulations include point and shaft resistance, alterations in porosity and stress fields and particles displacement. Several simulations were conducted in order to investigate the effects of different numerical approaches showing indications that the method of installation and particle rotation could influence greatly in the conditions around the numerical pile. Minor effects were also noted due to change in penetration velocity and pile-soil friction. The difference in behavior of a moving and a stationary pile shows good qualitative agreement with previous experimental results indicating the necessity of realizing a force equilibrium process prior to any load-test to be simulated.

  14. Simulation of triaxial response of granular materials by modified DEM

    Science.gov (United States)

    Wang, XiaoLiang; Li, JiaChun

    2014-12-01

    A modified discrete element method (DEM) with rolling effect taken into consideration is developed to examine macroscopic behavior of granular materials in this study. Dimensional analysis is firstly performed to establish the relationship between macroscopic mechanical behavior, mesoscale contact parameters at particle level and external loading rate. It is found that only four dimensionless parameters may govern the macroscopic mechanical behavior in bulk. The numerical triaxial apparatus was used to study their influence on the mechanical behavior of granular materials. The parametric study indicates that Poisson's ratio only varies with stiffness ratio, while Young's modulus is proportional to contact modulus and grows with stiffness ratio, both of which agree with the micromechanical model. The peak friction angle is dependent on both inter-particle friction angle and rolling resistance. The dilatancy angle relies on inter-particle friction angle if rolling stiffness coefficient is sufficiently large. Finally, we have recommended a calibration procedure for cohesionless soil, which was at once applied to the simulation of Chende sand using a series of triaxial compression tests. The responses of DEM model are shown in quantitative agreement with experiments. In addition, stress-strain response of triaxial extension was also obtained by numerical triaxial extension tests.

  15. Envolving the Operations of the TerraSAR-X/TanDEM-X Mission Planning System during the TanDEM-X Science Phase

    OpenAIRE

    Stathopoulos, Fotios; Guillermin, Guillaume; Garcia Acero, Carlos; Reich, Karin; Mrowka, Falk

    2016-01-01

    After the successful Global Coverage of the Digital Elevation Model, the TanDEM-X Science phase was initiated in September of 2014, dedicated to the demonstration of innovative techniques and experiments. The TanDEM-X Science phase had a large impact on the TerraSAR-X/TanDEM-X Mission Planning System. The two main challenges were the formation flying changes and the activation of a new acquisition mode, the so called Dual Receive Antenna (DRA) acquisition mode. This paper describes all action...

  16. Uncertainty of soil erosion modelling using open source high resolution and aggregated DEMs

    Directory of Open Access Journals (Sweden)

    Arun Mondal

    2017-05-01

    Full Text Available Digital Elevation Model (DEM is one of the important parameters for soil erosion assessment. Notable uncertainties are observed in this study while using three high resolution open source DEMs. The Revised Universal Soil Loss Equation (RUSLE model has been applied to analysis the assessment of soil erosion uncertainty using open source DEMs (SRTM, ASTER and CARTOSAT and their increasing grid space (pixel size from the actual. The study area is a part of the Narmada river basin in Madhya Pradesh state, which is located in the central part of India and the area covered 20,558 km2. The actual resolution of DEMs is 30 m and their increasing grid spaces are taken as 90, 150, 210, 270 and 330 m for this study. Vertical accuracy of DEMs has been assessed using actual heights of the sample points that have been taken considering planimetric survey based map (toposheet. Elevations of DEMs are converted to the same vertical datum from WGS 84 to MSL (Mean Sea Level, before the accuracy assessment and modelling. Results indicate that the accuracy of the SRTM DEM with the RMSE of 13.31, 14.51, and 18.19 m in 30, 150 and 330 m resolution respectively, is better than the ASTER and the CARTOSAT DEMs. When the grid space of the DEMs increases, the accuracy of the elevation and calculated soil erosion decreases. This study presents a potential uncertainty introduced by open source high resolution DEMs in the accuracy of the soil erosion assessment models. The research provides an analysis of errors in selecting DEMs using the original and increased grid space for soil erosion modelling.

  17. A photogrammetric DEM of Greenland based on 1978-1987 aerial photos: validation and integration with laser altimetry and satellite-derived DEMs

    DEFF Research Database (Denmark)

    Korsgaard, Niels Jákup; Kjær, Kurt H.; Nuth, Christopher

    Here we present a DEM of Greenland covering all ice-free terrain and the margins of the GrIS and local glaciers and ice caps. The DEM is based on the 3534 photos used in the aero-triangulation which were recorded by the Danish Geodata Agency (then the Geodetic Institute) in survey campaigns spann...... suggests that dynamically-induced mass loss started around 2003 and continued throughout 2014....

  18. Gedichte / [Konnula, Margus] Contra ; aus dem Estnischen von Gisbert Jänicke

    Index Scriptorium Estoniae

    Contra, pseud., 1974-

    2002-01-01

    Sisu : Die Nacht auf dem Busbahnhof = Öö bussijaamas ; Ich bin schwarz und schmutzig = Olen must ja räpane ; "wir sind da auf dem bild..." = "oleme siin pildi peal..." ; Lebensgrundlage = Elu alus ; Der Volksvertreter = Rahvaasemik ; Das Messer hinterm Rücken in der Hand = Selja taga nuga käes ; Wo = Kus ; Gute Nachbarn = Head naabrid

  19. Calibration of micromechanical parameters for DEM simulations by using the particle filter

    NARCIS (Netherlands)

    Cheng, Hongyang; Shuku, Takayuki; Thoeni, Klaus; Yamamoto, Haruyuki

    2017-01-01

    The calibration of DEM models is typically accomplished by trail and error. However, the procedure lacks of objectivity and has several uncertainties. To deal with these issues, the particle filter is employed as a novel approach to calibrate DEM models of granular soils. The posterior probability

  20. Was haben Feuertaufe, Deckung und Stellung gemeinsam? - Einigen Phrasemen aus dem Soldatenalltag auf der Spur

    Directory of Open Access Journals (Sweden)

    Urška Valenčič Arh

    2016-12-01

    Full Text Available Im vorliegenden Beitrag werden feste Wortverbindungen mit den Komponeten Feuertaufe, Deckung und Stellung unter lexikalischem und semantischem Aspekt dargestellt und einem diachronen Vergleich unterzogen. Als Untersuchungsmaterial dienen das authentische Kriegstagebuch aus dem I. Weltkrieg und Belege aus dem lexikographischen Korpus DWDS der gegenwärtigen deutschen Sprache.

  1. Zur Internationalität der Pädagogischen Psychologie aus dem deutschsprachigen Bereich

    OpenAIRE

    Krampen, Günter; Schui, Gabriel

    2007-01-01

    Vor dem Hintergrund der Internationalisierungsdebatte der Psychologie in den deutschsprachigen Ländern wird der Internationalisierungsgrad der Pädagogischen Psychologie im Vergleich zur gesamten psychologischen Forschung aus dem deutschsprachigen Bereich unter zwei Perspektiven bibliometrisch untersucht: Zum ersten geht es inhaltlich um die Entwicklung der englischsprachigen Anteile der in PSYNDEX unter der Klassifikation "Pädagogische Psychologie" dokumentierten Literatur, zum zweiten um Ana...

  2. Accuracy of Cartosat-1 DEM and its derived attribute at multiple ...

    Indian Academy of Sciences (India)

    Digital Elevation Model (DEM) provides basic information about terrain relief and is used for mor- phological characterisation, hydrological modelling and infrastructural studies. This paper investigates the accuracy of DEM and its derived attributes in multiple scales. This study was carried out for a part of Shiwalik Himalaya ...

  3. A BLENDING TECHNIQUE OF TOPOGRAHIC AND HYDROGRAPHIC DEMs FOR RIVER ALIGNMENT MODELLING

    Directory of Open Access Journals (Sweden)

    H. Karim

    2017-10-01

    Full Text Available Current practice in combining bathymetry and topographic DEM is based on overlaying and merging both datasets into a new DEM based on river boundary. Throughout a few sample of datasets from previous recent projects, authors realize that this method is not preserving the nature of natural river characteristic, especially at the slope in between riverbank and riverbed. Some arising issues were also highlighted; validity of the topographic DEM as well as the river boundary, limitations of DEMs and how bathymetry survey was carried out on field. To overcome these issues, a new technique called blending DEMs was proposed and tested to the project datasets. It is based on a fusion of two DEMs (with respective buffer, offset and fusion ratio from a validated river boundary to produce riverbank slope and a merging of two different interpolation results to produce a best riverbed DEM. Simple riverbank ontology was prescribed to illustrate the model enhancement in accuracy and visualization provided by this technique. The output from three projects/DEM results was presented as a comparison study between the current practices with the proposed technique.

  4. Dementia-free life expectancy (demFLE) in the Netherlands

    NARCIS (Netherlands)

    Perenboom, R.J.M.; Boshuizen, H.C.; Breteler, M.M.B.; Alewijn, O.; Water, H.P.A. van de

    1996-01-01

    To gain an insight into the burden of dementia in an aging society, life expectancy with dementia and its counterpart dementia-free life expectancy (DemFLE) in The Netherlands are presented. Sullivan's method was used to calculate DemFLE. For elderly living either independently or in homes for the

  5. Accuracy of Cartosat-1 DEM and its derived attribute at multiple ...

    Indian Academy of Sciences (India)

    Digital Elevation Model (DEM) provides basic information about terrain relief and is used for morphological characterisation, hydrological modelling and infrastructural studies. This paper investigates the accuracy of DEM and its derived attributes in multiple scales. This study was carried out for a part of Shiwalik Himalaya ...

  6. DEM simulation of non-spherical granular segregation in hopper

    Science.gov (United States)

    Tao, He; Zhong, Wenqi; Jin, Baosheng; Ren, Bing

    2013-07-01

    Discrete element model (DEM) was developed to simulate the non-spherical particles such as cornshaped particle, ellipsoidal particle and cylinder particle. Multi-element particle model was used to describe the non-spherical particle that means the non-spherical particle was constructed by several overlapping spheres. And the simulation was validated by the experiment. In addition, the flow characteristic of particle discharging in the hopper was researched for different diameter ratio. The result shows that the segregation phenomenon emerged as described in the previous researcher. The effect of the particle shape, particle diameter ratio and particle density ratio on the segregation was studied. The result shows that there is big difference of segregation for different particle shape. The extent of segregation for ellipsoidal particles is the largest, and that of the spherical particles is the smallest. The segregation extent increases significantly with the diameter ratio. And varying particle density ratios do not affect the segregation results significantly.

  7. DEM Simulation of Particle Stratification and Segregation in Stockpile Formation

    Science.gov (United States)

    Zhang, Dizhe; Zhou, Zongyan; Pinson, David

    2017-06-01

    Granular stockpiles are commonly observed in nature and industry, and their formation has been extensively investigated experimentally and mathematically in the literature. One of the striking features affecting properties of stockpiles are the internal patterns formed by the stratification and segregation processes. In this work, we conduct a numerical study based on DEM (discrete element method) model to study the influencing factors and triggering mechanisms of these two phenomena. With the use of a previously developed mixing index, the effects of parameters including size ratio, injection height and mass ratio are investigated. We found that it is a void-filling mechanism that differentiates the motions of particles with different sizes. This mechanism drives the large particles to flow over the pile surface and segregate at the pile bottom, while it also pushes small particles to fill the voids between large particles, giving rise to separate layers. Consequently, this difference in motion will result in the observed stratification and segregation phenomena.

  8. SPI Analysis of the Supernova Remnant DEM L71

    Science.gov (United States)

    Frank, Kari A.; Dwarkadas, Vikram; Burrows, David N.; Aisyah Mansoor, Siti; Crum, Ryan M.

    2017-08-01

    Supernova remnants are complex, three-dimensional objects; properly accounting for this complexity when modeling the resulting X-ray emission presents quite a challenge and makes it difficult to accurately characterize the properties of the full SNR volume. The SPIES (Smoothed Particle Inference Exploration of Supernova Remnants) project aims to address this challenge by applying a fundamentally different approach to analyzing X-ray observations of SNRs. Smoothed Particle Inference (SPI) is a Bayesian modeling process that fits a population of gas blobs ("smoothed particles") such that their superposed emission reproduces the observed spatial and spectral distribution of photons. We present here the results of an SPI analysis of the Type Ia supernova remnant DEM L71. Among other results, we find that despite its regular appearance, the temperature and other parameter maps exhibit irregular substructure.

  9. Validation of digital elevation models (DEMs) and comparison of geomorphic metrics on the southern Central Andean Plateau

    Science.gov (United States)

    Purinton, Benjamin; Bookhagen, Bodo

    2017-04-01

    In this study, we validate and compare elevation accuracy and geomorphic metrics of satellite-derived digital elevation models (DEMs) on the southern Central Andean Plateau. The plateau has an average elevation of 3.7 km and is characterized by diverse topography and relief, lack of vegetation, and clear skies that create ideal conditions for remote sensing. At 30 m resolution, SRTM-C, ASTER GDEM2, stacked ASTER L1A stereopair DEM, ALOS World 3D, and TanDEM-X have been analyzed. The higher-resolution datasets include 12 m TanDEM-X, 10 m single-CoSSC TerraSAR-X/TanDEM-X DEMs, and 5 m ALOS World 3D. These DEMs are state of the art for optical (ASTER and ALOS) and radar (SRTM-C and TanDEM-X) spaceborne sensors. We assessed vertical accuracy by comparing standard deviations of the DEM elevation versus 307 509 differential GPS measurements across 4000 m of elevation. For the 30 m DEMs, the ASTER datasets had the highest vertical standard deviation at > 6.5 m, whereas the SRTM-C, ALOS World 3D, and TanDEM-X were all radar DEMs (e.g., TanDEM-X) for geomorphometry are promising, but airborne or terrestrial data are still necessary for meter-scale analysis.

  10. INFLUENCE OF DEM IN WATERSHED MANAGEMENT AS FLOOD ZONATION MAPPING

    Directory of Open Access Journals (Sweden)

    M. Alrajhi

    2016-06-01

    Full Text Available Despite of valuable efforts from working groups and research organizations towards flood hazard reduction through its program, still minimal diminution from these hazards has been realized. This is mainly due to the fact that with rapid increase in population and urbanization coupled with climate change, flood hazards are becoming increasingly catastrophic. Therefore there is a need to understand and access flood hazards and develop means to deal with it through proper preparations, and preventive measures. To achieve this aim, Geographical Information System (GIS, geospatial and hydrological models were used as tools to tackle with influence of flash floods in the Kingdom of Saudi Arabia due to existence of large valleys (Wadis which is a matter of great concern. In this research paper, Digital Elevation Models (DEMs of different resolution (30m, 20m,10m and 5m have been used, which have proven to be valuable tool for the topographic parameterization of hydrological models which are the basis for any flood modelling process. The DEM was used as input for performing spatial analysis and obtaining derivative products and delineate watershed characteristics of the study area using ArcGIS desktop and its Arc Hydro extension tools to check comparability of different elevation models for flood Zonation mapping. The derived drainage patterns have been overlaid over aerial imagery of study area, to check influence of greater amount of precipitation which can turn into massive destructions. The flow accumulation maps derived provide zones of highest accumulation and possible flow directions. This approach provide simplified means of predicting extent of inundation during flood events for emergency action especially for large areas because of large coverage area of the remotely sensed data.

  11. ICESAT VALIDATION OF TANDEM-X I-DEMS OVER THE UK

    Directory of Open Access Journals (Sweden)

    L. Feng

    2016-06-01

    Full Text Available From the latest TanDEM-X mission (bistatic X-Band interferometric SAR, globally consistent Digital Elevation Model (DEM will be available from 2017, but their accuracy has not yet been fully characterised. This paper presents the methods and implementation of statistical procedures for the validation of the vertical accuracy of TanDEM-X iDEMs at grid-spacing of approximately 12.5 m, 30 m and 90 m based on processed ICESat data over the UK in order to assess their potential extrapolation across the globe. The accuracy of the TanDEM-X iDEM in UK was obtained as follows: against ICESat GLA14 elevation data, TanDEM-X iDEM has −0.028±3.654 m over England and Wales and 0.316 ± 5.286 m over Scotland for 12 m, −0.073 ± 6.575 m for 30 m, and 0.0225 ± 9.251 m at 90 m. Moreover, 90 % of all results at the three resolutions of TanDEM-X iDEM data (with a linear error at 90 % confidence level are below 16.2 m. These validation results also indicate that derivative topographic parameters (slope, aspect and relief have a strong effect on the vertical accuracy of the TanDEM-X iDEMs. In high-relief and large slope terrain, large errors and data voids are frequent, and their location is strongly influenced by topography, whilst in the low- to medium-relief and low slope sites, errors are smaller. ICESat derived elevations are heavily influenced by surface slope within the 70 m footprint as well as there being slope dependent errors in the TanDEM-X iDEMs.

  12. OPEN-SOURCE DIGITAL ELEVATION MODEL (DEMs EVALUATION WITH GPS AND LiDAR DATA

    Directory of Open Access Journals (Sweden)

    N. F. Khalid

    2016-09-01

    Full Text Available Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM, Shuttle Radar Topography Mission (SRTM, and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010 are freely available Digital Elevation Model (DEM datasets for environmental modeling and studies. The quality of spatial resolution and vertical accuracy of the DEM data source has a great influence particularly on the accuracy specifically for inundation mapping. Most of the coastal inundation risk studies used the publicly available DEM to estimated the coastal inundation and associated damaged especially to human population based on the increment of sea level. In this study, the comparison between ground truth data from Global Positioning System (GPS observation and DEM is done to evaluate the accuracy of each DEM. The vertical accuracy of SRTM shows better result against ASTER and GMTED10 with an RMSE of 6.054 m. On top of the accuracy, the correlation of DEM is identified with the high determination of coefficient of 0.912 for SRTM. For coastal zone area, DEMs based on airborne light detection and ranging (LiDAR dataset was used as ground truth data relating to terrain height. In this case, the LiDAR DEM is compared against the new SRTM DEM after applying the scale factor. From the findings, the accuracy of the new DEM model from SRTM can be improved by applying scale factor. The result clearly shows that the value of RMSE exhibit slightly different when it reached 0.503 m. Hence, this new model is the most suitable and meets the accuracy requirement for coastal inundation risk assessment using open source data. The suitability of these datasets for further analysis on coastal management studies is vital to assess the potentially vulnerable areas caused by coastal inundation.

  13. Accuracy assessment of the global TanDEM-X Digital Elevation Model with GPS data

    Science.gov (United States)

    Wessel, Birgit; Huber, Martin; Wohlfart, Christian; Marschalk, Ursula; Kosmann, Detlev; Roth, Achim

    2018-05-01

    The primary goal of the German TanDEM-X mission is the generation of a highly accurate and global Digital Elevation Model (DEM) with global accuracies of at least 10 m absolute height error (linear 90% error). The global TanDEM-X DEM acquired with single-pass SAR interferometry was finished in September 2016. This paper provides a unique accuracy assessment of the final TanDEM-X global DEM using two different GPS point reference data sets, which are distributed across all continents, to fully characterize the absolute height error. Firstly, the absolute vertical accuracy is examined by about three million globally distributed kinematic GPS (KGPS) points derived from 19 KGPS tracks covering a total length of about 66,000 km. Secondly, a comparison is performed with more than 23,000 "GPS on Bench Marks" (GPS-on-BM) points provided by the US National Geodetic Survey (NGS) scattered across 14 different land cover types of the US National Land Cover Data base (NLCD). Both GPS comparisons prove an absolute vertical mean error of TanDEM-X DEM smaller than ±0.20 m, a Root Means Square Error (RMSE) smaller than 1.4 m and an excellent absolute 90% linear height error below 2 m. The RMSE values are sensitive to land cover types. For low vegetation the RMSE is ±1.1 m, whereas it is slightly higher for developed areas (±1.4 m) and for forests (±1.8 m). This validation confirms an outstanding absolute height error at 90% confidence level of the global TanDEM-X DEM outperforming the requirement by a factor of five. Due to its extensive and globally distributed reference data sets, this study is of considerable interests for scientific and commercial applications.

  14. Sensitivity of Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations

    Science.gov (United States)

    2016-06-12

    buried in soil viz., (1) coupled discrete element & particle gas methods ( DEM -PGM) and (2) Arbitrary Lagrangian-Eulerian (ALE), are investigated. The...computational costs, inconsistent robustness and long run times, alternate modeling methods such as Smoothed Particle Hydrodynamics (SPH) [7] and DEM are gaining...DEM_PGM and identify the limitations/strengths compared to the ALE method. Discrete Element Method ( DEM ) can model individual particle directly, and

  15. Generation and performance assessment of the global TanDEM-X digital elevation model

    Science.gov (United States)

    Rizzoli, Paola; Martone, Michele; Gonzalez, Carolina; Wecklich, Christopher; Borla Tridon, Daniela; Bräutigam, Benjamin; Bachmann, Markus; Schulze, Daniel; Fritz, Thomas; Huber, Martin; Wessel, Birgit; Krieger, Gerhard; Zink, Manfred; Moreira, Alberto

    2017-10-01

    The primary objective of the TanDEM-X mission is the generation of a global, consistent, and high-resolution digital elevation model (DEM) with unprecedented global accuracy. The goal is achieved by exploiting the interferometric capabilities of the two twin SAR satellites TerraSAR-X and TanDEM-X, which fly in a close orbit formation, acting as an X-band single-pass interferometer. Between December 2010 and early 2015 all land surfaces have been acquired at least twice, difficult terrain up to seven or eight times. The acquisition strategy, data processing, and DEM calibration and mosaicking have been systematically monitored and optimized throughout the entire mission duration, in order to fulfill the specification. The processing of all data has finally been completed in September 2016 and this paper reports on the final performance of the TanDEM-X global DEM and presents the acquisition and processing strategy which allowed to obtain the final DEM quality. The results confirm the outstanding global accuracy of the delivered product, which can be now utilized for both scientific and commercial applications.

  16. A photogrammetric DEM of Greenland based on 1978-1987 aerial photos: validation and integration with laser altimetry and satellite-derived DEMs

    DEFF Research Database (Denmark)

    Korsgaard, Niels Jákup; Kjær, Kurt H.; Nuth, Christopher

    Here we present a DEM of Greenland covering all ice-free terrain and the margins of the GrIS and local glaciers and ice caps. The DEM is based on the 3534 photos used in the aero-triangulation which were recorded by the Danish Geodata Agency (then the Geodetic Institute) in survey campaigns...... spanning the period 1978-1987. The GrIS is covered tens of kilometers into the interior due to the large footprints of the photos (30 x 30 km) and control provided by the aero-triangulation. Thus, the data are ideal for providing information for analysis of ice marginal elevation change and also control...... for satellite-derived DEMs. The results of the validation, error assessments and predicted uncertainties are presented. We test the DEM using Airborne Topographic Mapper (IceBridge ATM) as reference data; evaluate the a posteriori covariance matrix from the aero-triangulation; and co-register DEM blocks of 50 x...

  17. CFD-DEM and Experimental Study of Bubbling in a Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Hassan A. Khawaja

    2015-12-01

    Full Text Available In this study, phenomenon of bubbling is investigated using CFD-DEM and experiments. A CFD-DEM simulation is setup to model the fluidized beds of different sizes. Geldart D particles of 1.2 mm diameter and 1000 Kg/m3 density are modelled. Study revealed different types of fluidization regimes as stated in the literature. An experimental setup is built to obtain the results for the comparison. Comparison revealed that results obtained from both methodologies; CFD-DEM and experiments are in reasonable agreement.

  18. Eröffnung des „Hauses der Astronomie“ auf dem Königsstuhl

    OpenAIRE

    Pössel, Markus; Tschira, Klaus

    2012-01-01

    Mit dem „Haus der Astronomie“ (HdA) auf dem Königsstuhl ist ein neues Zentrum für astronomische Bildungs- und Öffentlichkeitsarbeit in Heidelberg eröffnet. Das Haus der Astronomie ist eine gemeinsame Einrichtung der Max-Planck-Gesellschaft (MPG) und der Klaus Tschira Stiftung unter Beteiligung der Stadt Heidelberg und der Ruperto Carola, deren Zentrum für Astronomie eng mit dem HdA zusammenarbeitet. Ziel des HdA ist es, astronomische Forschung einer breiten Öffentlichkeit in verständlicher Fo...

  19. Discrete element simulation of mill charge in 3D using the BLAZE-DEM GPU framework

    CSIR Research Space (South Africa)

    Govender, Nicolin

    2015-08-01

    Full Text Available to implement our algorithm on the GPU. The flow-diagram in Figure 2 describes the DEM process that we model. The bulk of computational time is spent on neighbor searching and collision detection. 3 Figure 2: Flow chart of DEM simulation procedure. An assumption... in many DEM simulations is that particles are considered to be perfectly rigid for the duration of collision contact. In reality perfectly rigid particles do not exist, as all bodies will experience (to some extent) local deformations during contact...

  20. Morphological changes at Mt. Etna detected by TanDEM-X

    Science.gov (United States)

    Wegmuller, Urs; Bonforte, Alessandro; De Beni, Emanuela; Guglielmino, Francesco; Strozzi, Tazio

    2014-05-01

    We produced a DEM of the Mt. Etna volcano using TanDEM-X data collected on October 9, 2012. The TanDEM-X data were acquired in bistatic mode with TSX as master sensor and TDX as receive only sensor. The pre-existing SRTM DEM was used for geometrical reference (geocoding, initial height model, large scale reference). The interferogram was computed with 4 looks in range and 4 looks in azimuth. After compensation of the SRTM heights, the differential TanDEM-X interferogram looked overall quite flat but showed local deviations related to noise (e.g. over the sea), topographic effects related to the low resolution of the SRTM DEM, and deviations related to actual changes of the topography, as observed in the Mount Etna peak region. After phase unwrapping, addressed with a minimum-cost flow algorithm and slight spatial filtering, the unwrapped phases were converted to relative heights. In order to move to absolute heights the SRTM height reference was used under the assumption that the deviation from the SRTM DEM is zero at large scale and without any linear trend. Finally, the height model was resampled into geographical coordinates. In the framework of the MED-SUV project, and thanks to the availability of a dense GPS network of more than 100 benchmarks periodically measured by INGV_OE, the TanDEM-X model has been validated. By computing the difference of the elevations provided by TanDEM-X with those measured by GPS we obtained a mean difference of 0.7 m and a standard deviation of 5.2 m. These values are biased by a few GPS benchmarks located in steep areas unfavorable illuminated by the radar. Without considerations of the two more unfavorable GPS stations, the height mean difference and a standard deviation are 0.6 m and 4.3 m respectively. We also performed correlation analyses of the height differences with respect to topography, latitude and longitude and we could exclude any elevation-related errors or geometrical ramp distortions. In the following, we compared

  1. DEM Simulation of Particle Stratification and Segregation in Stockpile Formation

    Directory of Open Access Journals (Sweden)

    Zhang Dizhe

    2017-01-01

    Full Text Available Granular stockpiles are commonly observed in nature and industry, and their formation has been extensively investigated experimentally and mathematically in the literature. One of the striking features affecting properties of stockpiles are the internal patterns formed by the stratification and segregation processes. In this work, we conduct a numerical study based on DEM (discrete element method model to study the influencing factors and triggering mechanisms of these two phenomena. With the use of a previously developed mixing index, the effects of parameters including size ratio, injection height and mass ratio are investigated. We found that it is a void-filling mechanism that differentiates the motions of particles with different sizes. This mechanism drives the large particles to flow over the pile surface and segregate at the pile bottom, while it also pushes small particles to fill the voids between large particles, giving rise to separate layers. Consequently, this difference in motion will result in the observed stratification and segregation phenomena.

  2. DEM Simulation of Particle Clogging in Fiber Filtration

    Science.gov (United States)

    Tao, Ran; Yang, Mengmeng; Li, Shuiqing

    2015-11-01

    The formation of porous particle deposits plays a crucial role in determining the efficiency of filtration process. In this work, an adhesive discrete element method (DEM), in combination with CFD, is developed to dynamically describe these porous deposit structures and the changed flow field between two parallel fibers under the periodic boundary conditions. For the first time, it is clarified that the structures of clogged particles are dependent on both the adhesion parameter (defined as the ratio of interparticle adhesion to particle inertia) and the Stokes number (as an index of impaction efficiency). The relationship between the pressure-drop gradient and the coordination number along the filtration time is explored, which can be used to quantitatively classify the different filtration regimes, i.e., clean filter stage, clogging stage and cake filtration stage. Finally, we investigate the influence of the fiber separation distance on the particle clogging behavior, which affects the collecting efficiency of the fibers significantly. The results suggest that changing the arrangement of fibers can improve the filter performance. This work has been funded by the National Key Basic Research and Development Program (2013CB228506).

  3. Evaluation of DEM generation accuracy from UAS imagery

    Science.gov (United States)

    Santise, M.; Fornari, M.; Forlani, G.; Roncella, R.

    2014-06-01

    The growing use of UAS platform for aerial photogrammetry comes with a new family of Computer Vision highly automated processing software expressly built to manage the peculiar characteristics of these blocks of images. It is of interest to photogrammetrist and professionals, therefore, to find out whether the image orientation and DSM generation methods implemented in such software are reliable and the DSMs and orthophotos are accurate. On a more general basis, it is interesting to figure out whether it is still worth applying the standard rules of aerial photogrammetry to the case of drones, achieving the same inner strength and the same accuracies as well. With such goals in mind, a test area has been set up at the University Campus in Parma. A large number of ground points has been measured on natural as well as signalized points, to provide a comprehensive test field, to check the accuracy performance of different UAS systems. In the test area, points both at ground-level and features on the buildings roofs were measured, in order to obtain a distributed support also altimetrically. Control points were set on different types of surfaces (buildings, asphalt, target, fields of grass and bumps); break lines, were also employed. The paper presents the results of a comparison between two different surveys for DEM (Digital Elevation Model) generation, performed at 70 m and 140 m flying height, using a Falcon 8 UAS.

  4. Evaluation of DEM generation accuracy from UAS imagery

    Directory of Open Access Journals (Sweden)

    M. Santise

    2014-06-01

    Full Text Available The growing use of UAS platform for aerial photogrammetry comes with a new family of Computer Vision highly automated processing software expressly built to manage the peculiar characteristics of these blocks of images. It is of interest to photogrammetrist and professionals, therefore, to find out whether the image orientation and DSM generation methods implemented in such software are reliable and the DSMs and orthophotos are accurate. On a more general basis, it is interesting to figure out whether it is still worth applying the standard rules of aerial photogrammetry to the case of drones, achieving the same inner strength and the same accuracies as well. With such goals in mind, a test area has been set up at the University Campus in Parma. A large number of ground points has been measured on natural as well as signalized points, to provide a comprehensive test field, to check the accuracy performance of different UAS systems. In the test area, points both at ground-level and features on the buildings roofs were measured, in order to obtain a distributed support also altimetrically. Control points were set on different types of surfaces (buildings, asphalt, target, fields of grass and bumps; break lines, were also employed. The paper presents the results of a comparison between two different surveys for DEM (Digital Elevation Model generation, performed at 70 m and 140 m flying height, using a Falcon 8 UAS.

  5. 2012 Oregon Department of Geology and Mineral Industries (DOGAMI) Lidar DEM: Rogue River Oregon

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset encompasses portions of Coos, Curry, Douglas, Jackson, and Josephine Counties.The bare earth digital elevation model (DEM) represents the earth's surface...

  6. Greenland 5 km DEM, Ice Thickness, and Bedrock Elevation Grids, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — A Digital Elevation Model (DEM), ice thickness grid, and bedrock elevation grid of Greenland acquired as part of the PARCA program are available in ASCII text format...

  7. Automated sinkhole detection using a DEM subsetting technique and fill tools at Mammoth Cave National Park

    Science.gov (United States)

    Wall, J.; Bohnenstiehl, D. R.; Levine, N. S.

    2013-12-01

    An automated workflow for sinkhole detection is developed using Light Detection and Ranging (Lidar) data from Mammoth Cave National Park (MACA). While the park is known to sit within a karst formation, the generally dense canopy cover and the size of the park (~53,000 acres) creates issues for sinkhole inventorying. Lidar provides a useful remote sensing technology for peering beneath the canopy in hard to reach areas of the park. In order to detect sinkholes, a subsetting technique is used to interpolate a Digital Elevation Model (DEM) thereby reducing edge effects. For each subset, standard GIS fill tools are used to fill depressions within the DEM. The initial DEM is then subtracted from the filled DEM resulting in detected depressions or sinkholes. Resulting depressions are then described in terms of size and geospatial trend.

  8. VT Lidar Hydro-flattened DEM (0.7 meter) - 2014 - Chittenden, Lamoille, Orleans, & Washington Counties

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Eastern VT 2014 0.7m and Digital Elevation Model (DEM) dataset of the following...

  9. VT Lidar Hydro-flattened DEM (0.7 meter) - 2015 - Windham County

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Windham County 2015 0.7m and Digital Elevation Model (DEM) dataset of the following...

  10. High Mountain Asia 8-meter DEMs Derived from Cross-track Optical Imagery V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 8-meter Digital Elevation Model (DEM) mosaics of high mountain Asia glacier and snow regions generated from from very-high-resolution...

  11. VT Lidar Hydro-flattened DEM (1.6 meter) - 2010 - East Franklin/West Orleans

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and Digital Elevation Model (DEM) datasets of various...

  12. Como diagnosticar as quatro causas mais freqüentes de demência?

    OpenAIRE

    Caramelli,Paulo; Barbosa,Maira Tonidandel

    2002-01-01

    Doença de Alzheimer, demência vascular, demência com corpos de Lewy e demência frontotemporal são as quatro causas mais freqüentes de demência na prática clínica. O diagnóstico diferencial dessas condições se baseia na busca de perfis clínicos característicos por anamnese adequada, exame neurológico e avaliação neuropsicológica, além de investigação complementar pertinente, que consiste em exames laboratoriais e de neuroimagem. O presente artigo apresenta breve revisão das características pri...

  13. GLACIER VOLUME CHANGE ESTIMATION USING TIME SERIES OF IMPROVED ASTER DEMS

    Directory of Open Access Journals (Sweden)

    L. Girod

    2016-06-01

    Full Text Available Volume change data is critical to the understanding of glacier response to climate change. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER system embarked on the Terra (EOS AM-1 satellite has been a unique source of systematic stereoscopic images covering the whole globe at 15m resolution and at a consistent quality for over 15 years. While satellite stereo sensors with significantly improved radiometric and spatial resolution are available to date, the potential of ASTER data lies in its long consistent time series that is unrivaled, though not fully exploited for change analysis due to lack of data accuracy and precision. Here, we developed an improved method for ASTER DEM generation and implemented it in the open source photogrammetric library and software suite MicMac. The method relies on the computation of a rational polynomial coefficients (RPC model and the detection and correction of cross-track sensor jitter in order to compute DEMs. ASTER data are strongly affected by attitude jitter, mainly of approximately 4 km and 30 km wavelength, and improving the generation of ASTER DEMs requires removal of this effect. Our sensor modeling does not require ground control points and allows thus potentially for the automatic processing of large data volumes. As a proof of concept, we chose a set of glaciers with reference DEMs available to assess the quality of our measurements. We use time series of ASTER scenes from which we extracted DEMs with a ground sampling distance of 15m. Our method directly measures and accounts for the cross-track component of jitter so that the resulting DEMs are not contaminated by this process. Since the along-track component of jitter has the same direction as the stereo parallaxes, the two cannot be separated and the elevations extracted are thus contaminated by along-track jitter. Initial tests reveal no clear relation between the cross-track and along-track components so that the latter

  14. Sterblichkeit: der paradoxe Kunstgriff des Lebens - Eine Betrachtung vor dem Hintergrund der modernen Biologie

    Science.gov (United States)

    Verbeek, Bernhard

    Leben gibt es auf der Erde seit fast 4 Mio. Jahren, trotz allen Katastrophen. Die Idee des Lebens scheint unsterblich. Der Tod aber offenbar auch. Jedes Lebewesen ist davon bedroht, ja für Menschen und andere "höhere“ Lebewesen ist er im Lebensprogramm eingebaut - todsicher. Diese Tatsache ist alles andere als selbstverständlich. Ist sie überhaupt kompatibel mit dem Prinzip der Evolution, nach dem der am besten Angepasste überlebt?

  15. An algorithm to extract more accurate stream longitudinal profiles from unfilled DEMs

    Science.gov (United States)

    Byun, Jongmin; Seong, Yeong Bae

    2015-08-01

    Morphometric features observed from a stream longitudinal profile (SLP) reflect channel responses to lithological variation and changes in uplift or climate; therefore, they constitute essential indicators in the studies for the dynamics between tectonics, climate, and surface processes. The widespread availability of digital elevation models (DEMs) and their processing enable semi-automatic extraction of SLPs as well as additional stream profile parameters, thus reducing the time spent for extracting them and simultaneously allowing regional-scale studies of SLPs. However, careful consideration is required to extract SLPs directly from a DEM, because the DEM must be altered by depression filling process to ensure the continuity of flows across it. Such alteration inevitably introduces distortions to the SLP, such as stair steps, bias of elevation values, and inaccurate stream paths. This paper proposes a new algorithm, called maximum depth tracing algorithm (MDTA), to extract more accurate SLPs using depression-unfilled DEMs. The MDTA supposes that depressions in DEMs are not necessarily artifacts to be removed, and that elevation values within them are useful to represent more accurately the real landscape. To ensure the continuity of flows even across the unfilled DEM, the MDTA first determines the outlet of each depression and then reverses flow directions of the cells on the line of maximum depth within each depression, beginning from the outlet and toward the sink. It also calculates flow accumulation without disruption across the unfilled DEM. Comparative analysis with the profiles extracted by the hydrologic functions implemented in the ArcGIS™ was performed to illustrate the benefits from the MDTA. It shows that the MDTA provides more accurate stream paths on depression areas, and consequently reduces distortions of the SLPs derived from the paths, such as exaggerated elevation values and negatively biased slopes that are commonly observed in the SLPs

  16. Uncertainty of SWAT model at different DEM resolutions in a large mountainous watershed.

    Science.gov (United States)

    Zhang, Peipei; Liu, Ruimin; Bao, Yimeng; Wang, Jiawei; Yu, Wenwen; Shen, Zhenyao

    2014-04-15

    The objective of this study was to enhance understanding of the sensitivity of the SWAT model to the resolutions of Digital Elevation Models (DEMs) based on the analysis of multiple evaluation indicators. The Xiangxi River, a large tributary of Three Gorges Reservoir in China, was selected as the study area. A range of 17 DEM spatial resolutions, from 30 to 1000 m, was examined, and the annual and monthly model outputs based on each resolution were compared. The following results were obtained: (i) sediment yield was greatly affected by DEM resolution; (ii) the prediction of dissolved oxygen load was significantly affected by DEM resolutions coarser than 500 m; (iii) Total Nitrogen (TN) load was not greatly affected by the DEM resolution; (iv) Nitrate Nitrogen (NO₃-N) and Total Phosphorus (TP) loads were slightly affected by the DEM resolution; and (v) flow and Ammonia Nitrogen (NH₄-N) load were essentially unaffected by the DEM resolution. The flow and dissolved oxygen load decreased more significantly in the dry season than in the wet and normal seasons. Excluding flow and dissolved oxygen, the uncertainties of the other Hydrology/Non-point Source (H/NPS) pollution indicators were greater in the wet season than in the dry and normal seasons. Considering the temporal distribution uncertainties, the optimal DEM resolutions for flow was 30-200 m, for sediment and TP was 30-100 m, for dissolved oxygen and NO₃-N was 30-300 m, for NH₄-N was 30 to 70 m and for TN was 30-150 m. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. HELI-DEM portal for geo-processing services

    Science.gov (United States)

    Cannata, Massimiliano; Antonovic, Milan; Molinari, Monia

    2014-05-01

    HELI-DEM (Helvetia-Italy Digital Elevation Model) is a project developed in the framework of Italy/Switzerland Operational Programme for Trans-frontier Cooperation 2007-2013 whose major aim is to create a unified digital terrain model that includes the alpine and sub-alpine areas between Italy and Switzerland. The partners of the project are: Lombardy Region, Piedmont Region, Polytechnic of Milan, Polytechnic of Turin and Fondazione Politecnico from Italy; Institute of Earth Sciences (SUPSI) from Switzerland. The digital terrain model has been produced by integrating and validating the different elevation data available for the areas of interest, characterized by different reference frame, resolutions and accuracies: DHM at 25 m resolution from Swisstopo, DTM at 20 m resolution from Lombardy Region, DTM at 5 m resolution from Piedmont Region and DTM LiDAR PST-A at about 1 m resolution, that covers the main river bed areas and is produced by the Italian Ministry of the Environment. Further results of the project are: the generation of a unique Italian Swiss geoid with an accuracy of few centimeters (Gilardoni et al. 2012); the establishment of a GNSS permanent network, prototype of a transnational positioning service; the development of a geo-portal, entirely based on open source technologies and open standards, which provides the cross-border DTM and offers some capabilities of analysis and processing through the Internet. With this talk, the authors want to present the main steps of the project with a focus on the HELI-DEM geo-portal development carried out by the Institute of Earth Sciences, which is the access point to the DTM outputted from the project. The portal, accessible at http://geoservice.ist.supsi.ch/helidem, is a demonstration of open source technologies combined for providing access to geospatial functionalities to wide non GIS expert public. In fact, the system is entirely developed using only Open Standards and Free and Open Source Software (FOSS

  18. DEM simulation of granular flows in a centrifugal acceleration field

    Science.gov (United States)

    Cabrera, Miguel Angel; Peng, Chong; Wu, Wei

    2017-04-01

    The main purpose of mass-flow experimental models is abstracting distinctive features of natural granular flows, and allow its systematic study in the laboratory. In this process, particle size, space, time, and stress scales must be considered for the proper representation of specific phenomena [5]. One of the most challenging tasks in small scale models, is matching the range of stresses and strains among the particle and fluid media observed in a field event. Centrifuge modelling offers an alternative to upscale all gravity-driven processes, and it has been recently employed in the simulation of granular flows [1, 2, 3, 6, 7]. Centrifuge scaling principles are presented in Ref. [4], collecting a wide spectrum of static and dynamic models. However, for the case of kinematic processes, the non-uniformity of the centrifugal acceleration field plays a major role (i.e., Coriolis and inertial effects). In this work, we discuss a general formulation for the centrifugal acceleration field, implemented in a discrete element model framework (DEM), and validated with centrifuge experimental results. Conventional DEM simulations relate the volumetric forces as a function of the gravitational force Gp = mpg. However, in the local coordinate system of a rotating centrifuge model, the cylindrical centrifugal acceleration field needs to be included. In this rotating system, the centrifugal acceleration of a particle depends on the rotating speed of the centrifuge, as well as the position and speed of the particle in the rotating model. Therefore, we obtain the formulation of centrifugal acceleration field by coordinate transformation. The numerical model is validated with a series of centrifuge experiments of monodispersed glass beads, flowing down an inclined plane at different acceleration levels and slope angles. Further discussion leads to the numerical parameterization necessary for simulating equivalent granular flows under an augmented acceleration field. The premise of

  19. ASTER Global DEM contribution to GEOSS demonstrates open data sharing

    Science.gov (United States)

    Sohre, T.; Duda, K. A.; Meyer, D. J.; Behnke, J.; Nasa Esdis Lp Daac

    2010-12-01

    across all the GEOSS Societal Benefit areas was shown. The release of the global tiled research-grade DEM resulted in a significant increase in demand for ASTER elevation models, and increased awareness of related products. No cost access to these data has also promoted new applications of remotely sensed data, increasing their use across the full range of the GEOSS societal benefit areas. In addition, the simplified data access and greatly expanded pool of users resulted in a number of suggestions from researchers in many disciplines for possible enhancements to future versions of the ASTER GDEM. The broad distribution of the product can be directly attributed to the adoption of fundamental GEOSS data sharing principles, which are directed toward expanded access by minimizing time delay and cost, thus facilitating data use for education, research, and a range of other applications. The ASTER GDEM demonstrated the need and user demand for an improved global DEM product as well as the added benefit of not only “full and open” distribution, but “free and open” distribution.

  20. No Substitute for Going to the Field: Correcting Lidar DEMs in Salt Marshes

    Science.gov (United States)

    Renken, K.; Morris, J. T.; Lynch, J.; Bayley, H.; Neil, A.; Rasmussen, S.; Tyrrell, M.; Tanis, M.

    2016-12-01

    Models that forecast the response of salt marshes to current and future trends in sea level rise increasingly are used to guide management of these vulnerable ecosystems. Lidar-derived DEMs serve as the foundation for modeling landform change. However, caution is advised when using these DEMs as the starting point for models of salt marsh evolution. While broad vegetation class (i.e., young forest, old forest, grasslands, desert, etc.) has proven to be a significant predictor of vertical displacement error in terrestrial environments, differentiating error among different species or community types within the same ecosystem has received less attention. Salt marshes are dominated by monocultures of grass species and thus are an ideal environment to examine the within-species effect on lidar DEM error. We analyzed error of lidar DEMs using elevations from real-time kinematic (RTK) surveys in saltmarshes in multiple national parks and wildlife refuge areas from the mouth of the Chesapeake Bay to Massachusetts. Error of the lidar DEMs was sometimes large, on the order of 0.25 m, and varied significantly between sites because vegetation cover varies seasonally and lidar data was not always collected in the same season for each park. Vegetation cover and composition were used to explain differences between RTK elevations and lidar DEMs. This research underscores the importance of collecting RTK elevation data and vegetation cover data coincident with lidar data to produce correction factors specific to individual salt marsh sites.

  1. COMPARISON AND CO-REGISTRATION OF DEMS GENERATED FROM HiRISE AND CTX IMAGES

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2016-06-01

    Full Text Available Images from two sensors, the High-Resolution Imaging Science Experiment (HiRISE and the Context Camera (CTX, both on-board the Mars Reconnaissance Orbiter (MRO, were used to generate high-quality DEMs (Digital Elevation Models of the Martian surface. However, there were discrepancies between the DEMs generated from the images acquired by these two sensors due to various reasons, such as variations in boresight alignment between the two sensors during the flight in the complex environment. This paper presents a systematic investigation of the discrepancies between the DEMs generated from the HiRISE and CTX images. A combined adjustment algorithm is presented for the co-registration of HiRISE and CTX DEMs. Experimental analysis was carried out using the HiRISE and CTX images collected at the Mars Rover landing site and several other typical regions. The results indicated that there were systematic offsets between the HiRISE and CTX DEMs in the longitude and latitude directions. However, the offset in the altitude was less obvious. After combined adjustment, the offsets were eliminated and the HiRISE and CTX DEMs were co-registered to each other. The presented research is of significance for the synergistic use of HiRISE and CTX images for precision Mars topographic mapping.

  2. TanDEM-X the Earth surface observation project from space level - basis and mission status

    Directory of Open Access Journals (Sweden)

    Jerzy Wiśniowski

    2015-03-01

    Full Text Available TanDEM-X is DLR (Deutsches Zentrum für Luft- und Raumfahrt the Earth surface observation project using high-resolution SAR interferometry. It opens a new era in space borne radar remote sensing. The system is based on two satellites: TerraSAR-X (TSX and TanDEM-X (TDX flying on the very close, strictly controlled orbits. This paper gives an overview of the radar technology and overview of the TanDEM-X mission concept which is based on several innovative technologies. The primary objective of the mission is to deliver a global digital elevation model (DEM with an unprecedented accuracy, which is equal to or surpass the HRTI-3 specifications (12 m posting, relative height accuracy ±2 m for slope < 20% and ±4 m for slope > 20% [8]. Beyond that, TanDEM-X provides a highly reconfigurable platform for the demonstration of new radar imaging techniques and applications.[b]Keywords[/b]: remote sensing, Bistatic SAR, digital elevation model (DEM, Helix formation, SAR interferomery, HRTI-3, synchronization

  3. Recent Release of the ASTER Global DEM Product

    Science.gov (United States)

    Behnke, J.; Hall, A.; Meyer, D.; Sohre, T.; Doescher, C.

    2009-12-01

    On June 29th, the ASTER Global Digital Elevation Model (DEM) release was announced to the public and to a very eager audience. ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an imaging instrument flying on Terra, a satellite launched in December 1999 as part of NASA's Earth Observing System (EOS). ASTER is a cooperative effort between NASA, Japan's Ministry of Economy, Trade and Industry (METI) and Japan's Earth Remote Sensing Data Analysis Center (ERSDAC). On June 21, NASA Headquarters along with colleagues in Japan (METI) signed a plan for distribution of this product. The global digital elevation model of Earth is available online to users everywhere at no cost from NASA's Land Processes Distributed Active Archive Center (DAAC) located at Sioux Falls, SD. The DAAC is a joint project of NASA and the USGS and is a key component of NASA's EOSDIS. The new ASTER GDEM was created from nearly 1.3 million individual stereo-pair images acquired by the Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer (Aster) instrument aboard NASA’s Terra satellite. The ASTER elevation model was jointly developed by NASA and METI under contract to Sensor Information Laboratory Corp., Tsukuba, Japan. On June 29, the NASA press release was picked up quickly by numerous news organizations and online sites. Response to the product was incredible! The news of the release of the product was carried on websites across the globe, this fueled a tremendous response from users. Here are a few interesting metrics about the release: - over 41,000 unique visitors to website in first week following release - top countries in order were: US (approx. 20%), Germany, U.K., Brazil, Austria, Canada, Spain, Switzerland, Japan - approximately 29,000 visitors came to the news page in the first week and about 11,000 of these users downloaded the actual press release - by the end of August, over 2 Million ASTER GDEM files had been downloaded from the Land

  4. CFD-DEM simulations of current-induced dune formation and morphological evolution

    Science.gov (United States)

    Sun, Rui; Xiao, Heng

    2016-06-01

    Understanding the fundamental mechanisms of sediment transport, particularly those during the formation and evolution of bedforms, is of critical scientific importance and has engineering relevance. Traditional approaches of sediment transport simulations heavily rely on empirical models, which are not able to capture the physics-rich, regime-dependent behaviors of the process. With the increase of available computational resources in the past decade, CFD-DEM (computational fluid dynamics-discrete element method) has emerged as a viable high-fidelity method for the study of sediment transport. However, a comprehensive, quantitative study of the generation and migration of different sediment bed patterns using CFD-DEM is still lacking. In this work, current-induced sediment transport problems in a wide range of regimes are simulated, including 'flat bed in motion', 'small dune', 'vortex dune' and suspended transport. Simulations are performed by using SediFoam, an open-source, massively parallel CFD-DEM solver developed by the authors. This is a general-purpose solver for particle-laden flows tailed for particle transport problems. Validation tests are performed to demonstrate the capability of CFD-DEM in the full range of sediment transport regimes. Comparison of simulation results with experimental and numerical benchmark data demonstrates the merits of CFD-DEM approach. In addition, the improvements of the present simulations over existing studies using CFD-DEM are presented. The present solver gives more accurate prediction of sediment transport rate by properly accounting for the influence of particle volume fraction on the fluid flow. In summary, this work demonstrates that CFD-DEM is a promising particle-resolving approach for probing the physics of current-induced sediment transport.

  5. Visualization and comparison of DEM-derived parameters. Application to volcanic areas

    Science.gov (United States)

    Favalli, Massimiliano; Fornaciai, Alessandro

    2017-08-01

    Digital Elevation Models (DEMs) are fruitfully used in volcanology as the topographic base for mapping and quantifying volcanic landforms. The increasing availability of free topographic data on the web, decreasing production costs for high-accuracy data and advances in computer technology, has triggered rapid growth of the number of DEM users in the volcanological community. DEMs are often visualized only as hill-shaded maps, and while this is among the major advantages in using them, the possibility of deriving a very large number of parameters from a single grid of elevation data makes DEMs a powerful tool for morphometric analysis. However, many of these parameters have almost the same informative content, and before starting to elaborate topographic data it is recommended to know a-priori what parameters best visualize the investigated landform, and therefore what is necessary and what is redundant. In this work, we review a number of analytical procedures used to parameterize and represent DEMs. A LIDAR-derived DEM matrix acquired over the Valle del Bove valley, on Mt. Etna, is used as test-case elevation data for deriving the parameters. We first review well known parameters such as hill-shading, slope and aspect, curvature, and roughness, before extending the review to some less common parameters such as Sky View Factor (SVF), openness, and Red Relief Image Maps (RRIM). For each parameter a description is given emphasizing how it can be used for identifying and delimiting specific volcanic elements. The analyzed surface parameters are then cross-compared in order to infer which of them is most uncorrelated, and the results are represented in the form of a correlation matrix. Finally, the reviewed DEM-derived parameters and the correlation matrix are used for analyzing the volcanic landforms of two case studies: Michoacán-Guanajuato volcanic field and a phonolitic lava flow at the Island of Tenerife.

  6. Error modeling of DEMs from topographic surveys of rivers using fuzzy inference systems

    Science.gov (United States)

    Bangen, Sara; Hensleigh, James; McHugh, Peter; Wheaton, Joseph

    2016-02-01

    Digital elevation models (DEMs) have become common place in the earth sciences as a tool to characterize surface topography and set modeling boundary conditions. All DEMs have a degree of inherent error that is propagated to subsequent models and analyses. While previous research has shown that DEM error is spatially variable it is often represented as spatially uniform for analytical simplicity. Fuzzy inference systems (FIS) offer a tractable approach for modeling spatially variable DEM error, including flexibility in the number of inputs and calibration of outputs based on survey technique and modeling environment. We compare three FIS error models for DEMs derived from TS surveys of wadeable streams and test them at 34 sites in the Columbia River basin. The models differ in complexity regarding the number/type of inputs and degree of site-specific parameterization. A 2-input FIS uses inputs derived from the topographic point cloud (slope, point density). A 4-input FIS adds interpolation error and 3-D point quality. The 5-input FIS adds bed-surface roughness estimates. Both the 4 and 5-input FIS model output were parameterized to site-specific values. In the wetted channel we found (i) the 5-input FIS resulted in lower mean δz due to including roughness, and (ii) the 4 and 5-input FIS resulted in a higher standard deviation and maximum δz due to the inclusion of site-specific bank heights. All three FIS gave plausible estimates of DEM error, with the two more complicated models offering an improvement in the ability to detect spatially localized areas of DEM uncertainty.

  7. Co-Registration of Multi-Temporal dem Based on Sift Algorithm for Change Detection of Glaciers

    Science.gov (United States)

    Huang, Y.; Hu, Q.

    2017-09-01

    To detect the change of geographic objects by using multi-temporal DEM, the data must be co-registered firstly. In this paper, the Scale-Invariant Feature Transform (SIFT) algorithm is used to co-register multi-temporal DEM data and glacier change detection. Firstly, the DEM is converted into image space and extracts feature information, calculate multiple sets of match point coordinates, and achieve swift and accurate DEM data co-registration using SIFT algorithm. Secondly, the difference between co-registered DEM datasets are analysed. Total area change and average rate of change are calculated. Finally, the change of multi-temporal DEM data of glaciers in Langkazi County, Tibet from 2004 to 2014 is detected using the method proposed in this paper. The results indicate that the proposed method is able to detect change of the glaciers and the overall accuracy is higher than 85 %.

  8. Acute environmental toxicity and persistence of DEM, a chemical agent simulant: Diethyl malonate. [Diethyl malonate

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, D.A.; Ligotke, M.W.; Harvey, S.D.; Fellows, R.J.; Li, Shu-mei W.; Van Voris, P.; Wentsel, R.S.

    1990-05-01

    The purpose of the following chemical simulant studies is to assess the potential acute environmental effects and persistence of diethyl malonate (DEM). Deposition velocities for DEM to soil surfaces ranged from 0.04 to 0.2 cm/sec. For foliar surfaces, deposition velocities ranged from 0.0002 cm/sec at low air concentrations to 0.05 cm/sec for high dose levels. The residence times or half-lives of DEM deposited to soils was 2 h for the fast component and 5 to 16 h for the residual material. DEM deposited to foliar surfaces also exhibited biphasic depuration. The half-life of the short residence time component ranged from 1 to 3 h, while the longer time component had half-times of 16 to 242 h. Volatilization and other depuration mechanisms reduce surface contaminant levels in both soils and foliage to less than 1% of initial dose within 96 h. DEM is not phytotoxic at foliar mass loading levels of less than 10 {mu}m/cm{sup 2}. However, severe damage is evident at mass loading levels in excess of 17 {mu}g/cm{sup 2}. Tall fescue and sagebrush were more affected than was short-needle pine, however, mass loading levels were markedly different. Regrowth of tall fescue indicated that the effects of DEM are residual, and growth rates are affected only at higher mass loadings through the second harvest. Results from in vitro testing of DEM indicated concentrations below 500 {mu}g/g dry soil generally did not negatively impact soil microbial activity. Short-term effects of DEM were more profound on soil dehydrogenase activity than on soil phosphatase activity. No enzyme inhibition or enhancement was observed after 28 days in incubation. Results of the earthworm bioassay indicate survival to be 86 and 66% at soil doses of 107 and 204 {mu}g DEM/cm{sup 2}, respectively. At higher dose level, activity or mobility was judged to be affected in over 50% of the individuals. 21 refs., 10 figs., 15 tabs.

  9. Water body detection from TanDEM-X data: concept and first evaluation of an accurate water indication mask

    OpenAIRE

    Wendleder, Anna; Breunig, Markus; Klaus, Martin; Wessel, Birgit; Roth, Achim

    2011-01-01

    Additionally to the global DEM which is the main product of the TanDEM-X mission a global water body mask will be produced. The main goal of this water mask is to deliver an information layer for any subsequent DEM editing process. It is derived from the SAR amplitude and coherence. In this paper, the concept of the global water body detection is explained and a first evaluation of the single coverage water body detection is presented.

  10. Automatic relative RPC image model bias compensation through hierarchical image matching for improving DEM quality

    Science.gov (United States)

    Noh, Myoung-Jong; Howat, Ian M.

    2018-02-01

    The quality and efficiency of automated Digital Elevation Model (DEM) extraction from stereoscopic satellite imagery is critically dependent on the accuracy of the sensor model used for co-locating pixels between stereo-pair images. In the absence of ground control or manual tie point selection, errors in the sensor models must be compensated with increased matching search-spaces, increasing both the computation time and the likelihood of spurious matches. Here we present an algorithm for automatically determining and compensating the relative bias in Rational Polynomial Coefficients (RPCs) between stereo-pairs utilizing hierarchical, sub-pixel image matching in object space. We demonstrate the algorithm using a suite of image stereo-pairs from multiple satellites over a range stereo-photogrammetrically challenging polar terrains. Besides providing a validation of the effectiveness of the algorithm for improving DEM quality, experiments with prescribed sensor model errors yield insight into the dependence of DEM characteristics and quality on relative sensor model bias. This algorithm is included in the Surface Extraction through TIN-based Search-space Minimization (SETSM) DEM extraction software package, which is the primary software used for the U.S. National Science Foundation ArcticDEM and Reference Elevation Model of Antarctica (REMA) products.

  11. Uncertainty modelling and analysis of volume calculations based on a regular grid digital elevation model (DEM)

    Science.gov (United States)

    Li, Chang; Wang, Qing; Shi, Wenzhong; Zhao, Sisi

    2018-05-01

    The accuracy of earthwork calculations that compute terrain volume is critical to digital terrain analysis (DTA). The uncertainties in volume calculations (VCs) based on a DEM are primarily related to three factors: 1) model error (ME), which is caused by an adopted algorithm for a VC model, 2) discrete error (DE), which is usually caused by DEM resolution and terrain complexity, and 3) propagation error (PE), which is caused by the variables' error. Based on these factors, the uncertainty modelling and analysis of VCs based on a regular grid DEM are investigated in this paper. Especially, how to quantify the uncertainty of VCs is proposed by a confidence interval based on truncation error (TE). In the experiments, the trapezoidal double rule (TDR) and Simpson's double rule (SDR) were used to calculate volume, where the TE is the major ME, and six simulated regular grid DEMs with different terrain complexity and resolution (i.e. DE) were generated by a Gauss synthetic surface to easily obtain the theoretical true value and eliminate the interference of data errors. For PE, Monte-Carlo simulation techniques and spatial autocorrelation were used to represent DEM uncertainty. This study can enrich uncertainty modelling and analysis-related theories of geographic information science.

  12. Sedimentary Environments Mapping in the Yellow Sea Using TanDEM-X and Optic Satellites

    Science.gov (United States)

    Ryu, J. H.; Lee, Y. K.; Kim, S. W.

    2017-12-01

    Due to land reclamation and dredging, 57% of China's coastal wetlands have disappeared since the 1950s, and the total area of tidal flats in South Korea decreased from approximately 2,800km2 in 1990 to 2392km2 in 2005(Qiu, 2011 and MLTM, 2010). Intertidal DEM and sedimentary facies are useful for understanding intertidal functions and monitoring their response to natural and anthropogenic actions. Highly accurate intertidal DEMs with 5-m resolution were generated based on the TanDEM-X interferometric SAR (InSAR) technique because TanDEM-X allows the acquisition of the coherent InSAR pairs with no time lag or approximately 10-second temporal baseline between master and slave SAR image. We successfully generated intertidal zone DEMs with 5-7-m spatial resolutions and interferometric height accuracies better than 0.15 m for three representative tidal flats on the west coast of the Korean Peninsula and one site of chinese coastal region in the Yellow Sea. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures. The earlier studies have some limitation that the classification map is not considered to analysis various environmental conditions. Therefore, the purpose of this study was minutely to mapping the surface sedimentary facies by analyzing the tidal channel, topography with multi-sensor remotely sensed data and in-situ data.

  13. Dem Generation from Close-Range Photogrammetry Using Extended Python Photogrammetry Toolbox

    Science.gov (United States)

    Belmonte, A. A.; Biong, M. M. P.; Macatulad, E. G.

    2017-10-01

    Digital elevation models (DEMs) are widely used raster data for different applications concerning terrain, such as for flood modelling, viewshed analysis, mining, land development, engineering design projects, to name a few. DEMs can be obtained through various methods, including topographic survey, LiDAR or photogrammetry, and internet sources. Terrestrial close-range photogrammetry is one of the alternative methods to produce DEMs through the processing of images using photogrammetry software. There are already powerful photogrammetry software that are commercially-available and can produce high-accuracy DEMs. However, this entails corresponding cost. Although, some of these software have free or demo trials, these trials have limits in their usable features and usage time. One alternative is the use of free and open-source software (FOSS), such as the Python Photogrammetry Toolbox (PPT), which provides an interface for performing photogrammetric processes implemented through python script. For relatively small areas such as in mining or construction excavation, a relatively inexpensive, fast and accurate method would be advantageous. In this study, PPT was used to generate 3D point cloud data from images of an open pit excavation. The PPT was extended to add an algorithm converting the generated point cloud data into a usable DEM.

  14. FUSION OF MULTI-SCALE DEMS FROM DESCENT AND NAVCM IMAGES OF CHANG’E-3 USING COMPRESSED SENSING METHOD

    Directory of Open Access Journals (Sweden)

    M. Peng

    2017-07-01

    Full Text Available The multi-source DEMs generated using the images acquired in the descent and landing phase and after landing contain supplementary information, and this makes it possible and beneficial to produce a higher-quality DEM through fusing the multi-scale DEMs. The proposed fusion method consists of three steps. First, source DEMs are split into small DEM patches, then the DEM patches are classified into a few groups by local density peaks clustering. Next, the grouped DEM patches are used for sub-dictionary learning by stochastic coordinate coding. The trained sub-dictionaries are combined into a dictionary for sparse representation. Finally, the simultaneous orthogonal matching pursuit (SOMP algorithm is used to achieve sparse representation. We use the real DEMs generated from Chang’e-3 descent images and navigation camera (Navcam stereo images to validate the proposed method. Through the experiments, we have reconstructed a seamless DEM with the highest resolution and the largest spatial coverage among the input data. The experimental results demonstrated the feasibility of the proposed method.

  15. Blaze-DEMGPU: Modular high performance DEM framework for the GPU architecture

    Science.gov (United States)

    Govender, Nicolin; Wilke, Daniel N.; Kok, Schalk

    Blaze-DEMGPU is a modular GPU based discrete element method (DEM) framework that supports polyhedral shaped particles. The high level performance is attributed to the light weight and Single Instruction Multiple Data (SIMD) that the GPU architecture offers. Blaze-DEMGPU offers suitable algorithms to conduct DEM simulations on the GPU and these algorithms can be extended and modified. Since a large number of scientific simulations are particle based, many of the algorithms and strategies for GPU implementation present in Blaze-DEMGPU can be applied to other fields. Blaze-DEMGPU will make it easier for new researchers to use high performance GPU computing as well as stimulate wider GPU research efforts by the DEM community.

  16. FEM × DEM: a new efficient multi-scale approach for geotechnical problems with strain localization

    Science.gov (United States)

    Nguyen, Trung Kien; Claramunt, Albert Argilaga; Caillerie, Denis; Combe, Gaël; Dal Pont, Stefano; Desrues, Jacques; Richefeu, Vincent

    2017-06-01

    The paper presents a multi-scale modeling of Boundary Value Problem (BVP) approach involving cohesive-frictional granular materials in the FEM × DEM multi-scale framework. On the DEM side, a 3D model is defined based on the interactions of spherical particles. This DEM model is built through a numerical homogenization process applied to a Volume Element (VE). It is then paired with a Finite Element code. Using this numerical tool that combines two scales within the same framework, we conducted simulations of biaxial and pressuremeter tests on a cohesive-frictional granular medium. In these cases, it is known that strain localization does occur at the macroscopic level, but since FEMs suffer from severe mesh dependency as soon as shear band starts to develop, the second gradient regularization technique has been used. As a consequence, the objectivity of the computation with respect to mesh dependency is restored.

  17. Diagnostic of the temperature and differential emission measure (DEM based on Hinode/XRT data

    Directory of Open Access Journals (Sweden)

    P. Rudawy

    2008-10-01

    Full Text Available We discuss here various methodologies and an optimal strategy of the temperature and emission measure diagnostics based on Hinode X-Ray Telescope data. As an example of our results we present the determination of the temperature distribution of the X-rays emitting plasma using a filters ratio method and three various methods of the calculation of the differential emission measure (DEM. We have found that all these methods give results similar to the two filters ratio method. Additionally, all methods of the DEM calculation gave similar solutions. We can state that the majority of the pairs of the Hinode filters allows one to derive the temperature and emission measure in the isothermal plasma approximation using standard diagnostics based on the two filters ratio method. In cases of strong flares one can also expect good conformity of the results obtained using a Withbroe – Sylwester, genetic algorithm and least-squares methods of the DEM evaluation.

  18. Blaze-DEMGPU: Modular high performance DEM framework for the GPU architecture

    Directory of Open Access Journals (Sweden)

    Nicolin Govender

    2016-01-01

    Full Text Available Blaze-DEMGPU is a modular GPU based discrete element method (DEM framework that supports polyhedral shaped particles. The high level performance is attributed to the light weight and Single Instruction Multiple Data (SIMD that the GPU architecture offers. Blaze-DEMGPU offers suitable algorithms to conduct DEM simulations on the GPU and these algorithms can be extended and modified. Since a large number of scientific simulations are particle based, many of the algorithms and strategies for GPU implementation present in Blaze-DEMGPU can be applied to other fields. Blaze-DEMGPU will make it easier for new researchers to use high performance GPU computing as well as stimulate wider GPU research efforts by the DEM community.

  19. Granular dynamics, contact mechanics and particle system simulations a DEM study

    CERN Document Server

    Thornton, Colin

    2015-01-01

    This book is devoted to the Discrete Element Method (DEM) technique, a discontinuum modelling approach that takes into account the fact that granular materials are composed of discrete particles which interact with each other at the microscale level. This numerical simulation technique can be used both for dispersed systems in which the particle-particle interactions are collisional and compact systems of particles with multiple enduring contacts. The book provides an extensive and detailed explanation of the theoretical background of DEM. Contact mechanics theories for elastic, elastic-plastic, adhesive elastic and adhesive elastic-plastic particle-particle interactions are presented. Other contact force models are also discussed, including corrections to some of these models as described in the literature, and important areas of further research are identified. A key issue in DEM simulations is whether or not a code can reliably simulate the simplest of systems, namely the single particle oblique impact wit...

  20. Diálise - demência: estudo eletrencefalográfico de um caso

    Directory of Open Access Journals (Sweden)

    Duilton de Paola

    1980-09-01

    Full Text Available Relato de um caso de insuficiência renal crônica, mantido em hemodiálise por vários anos, desenvolvendo demência e alterações eletrencefalográficas típicas da síndrome diálise-demência. O eletrencefalograma apresentava paroxismos de ondas "sharp" e lentas difusas, elevado potencial os quais desapareceram com o tratamento, permanecendo o traçado apenas irregular. Houve melhora também da demência. Na tentativa de retirar o diazepínico, houve recrudescência dos sintomas. São comentados os aspectos clínicos e eletrencefalográficos da síndrome.

  1. FEM × DEM: a new efficient multi-scale approach for geotechnical problems with strain localization

    Directory of Open Access Journals (Sweden)

    Nguyen Trung Kien

    2017-01-01

    Full Text Available The paper presents a multi-scale modeling of Boundary Value Problem (BVP approach involving cohesive-frictional granular materials in the FEM × DEM multi-scale framework. On the DEM side, a 3D model is defined based on the interactions of spherical particles. This DEM model is built through a numerical homogenization process applied to a Volume Element (VE. It is then paired with a Finite Element code. Using this numerical tool that combines two scales within the same framework, we conducted simulations of biaxial and pressuremeter tests on a cohesive-frictional granular medium. In these cases, it is known that strain localization does occur at the macroscopic level, but since FEMs suffer from severe mesh dependency as soon as shear band starts to develop, the second gradient regularization technique has been used. As a consequence, the objectivity of the computation with respect to mesh dependency is restored.

  2. DEM simulations of bi-disperse ellipsoids of different particle sizes

    Science.gov (United States)

    Ng, Tang-Tat; Zhou, Wei

    2014-03-01

    This paper presents the result of two schemes concerning computational effort reduction in discrete element simulations (DEM) of binary mixtures. Numerical triaxial compression simulations were performed. The coarse ellipsoids and the fine ellipsoids have similar shapes, but the sizes are significantly different. Computational effort reduction can be achieved by increasing the density of individual particles so that a greater time step can be used in DEM. Two different mass increase schemes are investigated. The result indicates that both schemes provide a speedup. Similar results can be produced with the correct damping.

  3. On the choice of a phase interchange strategy for a multiscale DEM-VOF method

    Science.gov (United States)

    Pozzetti, Gabriele; Peters, Bernhard

    2017-07-01

    In this work a novel Multiscale DEM-VOF method is adopted to study three phase flows. It consists in solving the fluid momentum, mass conservation and the phase advection at a different scale with respect to the fluid-particle coupling problem. This allows the VOF scheme to resolve smaller fluid structures than a classic DEM-VOF method, and opens the possibility of adopting different volume interchange techniques. Two different volume interchange techniques are here described and compared with reference to high and low particle concentration scenarios. Considerations about the respective computational costs are also proposed.

  4. Developmental Eye Movement (DEM Test Norms for Mandarin Chinese-Speaking Chinese Children.

    Directory of Open Access Journals (Sweden)

    Yachun Xie

    Full Text Available The Developmental Eye Movement (DEM test is commonly used as a clinical visual-verbal ocular motor assessment tool to screen and diagnose reading problems at the onset. No established norm exists for using the DEM test with Mandarin Chinese-speaking Chinese children. This study aims to establish the normative values of the DEM test for the Mandarin Chinese-speaking population in China; it also aims to compare the values with three other published norms for English-, Spanish-, and Cantonese-speaking Chinese children. A random stratified sampling method was used to recruit children from eight kindergartens and eight primary schools in the main urban and suburban areas of Nanjing. A total of 1,425 Mandarin Chinese-speaking children aged 5 to 12 years took the DEM test in Mandarin Chinese. A digital recorder was used to record the process. All of the subjects completed a symptomatology survey, and their DEM scores were determined by a trained tester. The scores were computed using the formula in the DEM manual, except that the "vertical scores" were adjusted by taking the vertical errors into consideration. The results were compared with the three other published norms. In our subjects, a general decrease with age was observed for the four eye movement indexes: vertical score, adjusted horizontal score, ratio, and total error. For both the vertical and adjusted horizontal scores, the Mandarin Chinese-speaking children completed the tests much more quickly than the norms for English- and Spanish-speaking children. However, the same group completed the test slightly more slowly than the norms for Cantonese-speaking children. The differences in the means were significant (P0.05; compared with Spanish-speaking children, the scores were statistically significant (P0.05. DEM norms may be affected by differences in language, cultural, and educational systems among various ethnicities. The norms of the DEM test are proposed for use with Mandarin Chinese

  5. Rehkitzrettung mit dem Fliegenden Wildretter: Erfahrungen der ersten Feldeinsätze

    OpenAIRE

    Wimmer, Tilman; Israel, Martin; Haschberger, Peter; Weimann, Anita

    2013-01-01

    Der Fliegende Wildretter des Deutschen Zentrums für Luft- und Raumfahrt ist als prototypische Kleinserie seit dem Jahr 2010 erfolgreich in Deutsch-land und Österreich im Einsatz, um aus der Luft Wildtiere während der Wiesenmahd aufzuspüren, und diese so vor dem Tod durch das Mähwerk zu retten. Der Prototyp basiert auf einem ferngesteuerten Multikopter, der mit mehreren Kameras ausgestattet ist und damit im Flug zuverlässiger und wesentlich schneller Wildtiere er-kennen kann, als dies mit b...

  6. Bayesian calibration of microCT-based DEM simulations for predicting the effective elastic response of granular materials

    NARCIS (Netherlands)

    Cheng, Hongyang; Pellegrino, Antonio; Magnanimo, Vanessa

    2017-01-01

    A novel approach is presented for calibrating discrete element method (DEM) simulations of granular materials based on the sequential Bayesian parameter estimation over the experimental stress–strain responses. The initial DEM packing is bridged with microscopic computed tomography (microCT) images

  7. Lidar DEM error analyses and topographic depression identification in a hummocky landscape in the prairie region of Canada

    NARCIS (Netherlands)

    Li, S.; MacMillan, R.A.; Lobb, D.A.; McConkey, B.G.; Moulin, A.; Fraser, W.R.

    2011-01-01

    Topographic depressions are abundant in topographically complex landscapes. A common practice with earlier, low resolution Digital Elevation Models (DEMs) was to remove all depressions to ensure that water flowed continuously to the edge of the DEM domain. The assumption was that most depressions

  8. Development of a LiDAR derived digital elevation model (DEM) as Input to a METRANS geographic information system (GIS).

    Science.gov (United States)

    2011-05-01

    This report describes an assessment of digital elevation models (DEMs) derived from : LiDAR data for a subset of the Ports of Los Angeles and Long Beach. A methodology : based on Monte Carlo simulation was applied to investigate the accuracy of DEMs ...

  9. High-Accuracy Tidal Flat Digital Elevation Model Construction Using TanDEM-X Science Phase Data

    Science.gov (United States)

    Lee, Seung-Kuk; Ryu, Joo-Hyung

    2017-01-01

    This study explored the feasibility of using TanDEM-X (TDX) interferometric observations of tidal flats for digital elevation model (DEM) construction. Our goal was to generate high-precision DEMs in tidal flat areas, because accurate intertidal zone data are essential for monitoring coastal environment sand erosion processes. To monitor dynamic coastal changes caused by waves, currents, and tides, very accurate DEMs with high spatial resolution are required. The bi- and monostatic modes of the TDX interferometer employed during the TDX science phase provided a great opportunity for highly accurate intertidal DEM construction using radar interferometry with no time lag (bistatic mode) or an approximately 10-s temporal baseline (monostatic mode) between the master and slave synthetic aperture radar image acquisitions. In this study, DEM construction in tidal flat areas was first optimized based on the TDX system parameters used in various TDX modes. We successfully generated intertidal zone DEMs with 57-m spatial resolutions and interferometric height accuracies better than 0.15 m for three representative tidal flats on the west coast of the Korean Peninsula. Finally, we validated these TDX DEMs against real-time kinematic-GPS measurements acquired in two tidal flat areas; the correlation coefficient was 0.97 with a root mean square error of 0.20 m.

  10. Generation of a high-accuracy regional DEM based on ALOS/PRISM imagery of East Antarctica

    Science.gov (United States)

    Shiramizu, Kaoru; Doi, Koichiro; Aoyama, Yuichi

    2017-12-01

    A digital elevation model (DEM) is used to estimate ice-flow velocities for an ice sheet and glaciers via Differential Interferometric Synthetic Aperture Radar (DInSAR) processing. The accuracy of DInSAR-derived displacement estimates depends upon the accuracy of the DEM. Therefore, we used stereo optical images, obtained with a panchromatic remote-sensing instrument for stereo mapping (PRISM) sensor mounted onboard the Advanced Land Observing Satellite (ALOS), to produce a new DEM ("PRISM-DEM") of part of the coastal region of Lützow-Holm Bay in Dronning Maud Land, East Antarctica. We verified the accuracy of the PRISM-DEM by comparing ellipsoidal heights with those of existing DEMs and values obtained by satellite laser altimetry (ICESat/GLAS) and Global Navigation Satellite System surveying. The accuracy of the PRISM-DEM is estimated to be 2.80 m over ice sheet, 4.86 m over individual glaciers, and 6.63 m over rock outcrops. By comparison, the estimated accuracy of the ASTER-GDEM, widely used in polar regions, is 33.45 m over ice sheet, 14.61 m over glaciers, and 19.95 m over rock outcrops. For displacement measurements made along the radar line-of-sight by DInSAR, in conjunction with ALOS/PALSAR data, the accuracy of the PRISM-DEM and ASTER-GDEM correspond to estimation errors of <6.3 mm and <31.8 mm, respectively.

  11. TecDEM: A MATLAB based toolbox for tectonic geomorphology, Part 2: Surface dynamics and basin analysis

    Science.gov (United States)

    Shahzad, Faisal; Gloaguen, Richard

    2011-02-01

    We present the analytical capability of TecDEM, a MATLAB toolbox used in conjunction with Global DEMs for the extraction of tectonic geomorphologic information. TecDEM includes a suite of algorithms to analyze topography, extracted drainage networks and sub-basins. The aim of part 2 of this paper series is the generation of morphometric maps for surface dynamics and basin analysis. TecDEM therefore allows the extraction of parameters such as isobase, incision, drainage density and surface roughness maps. We also provide tools for basin asymmetry and hypsometric analysis. These are efficient graphical user interfaces (GUIs) for mapping drainage deviation from basin mid-line and basin hypsometry. A morphotectonic interpretation of the Kaghan Valley (Northern Pakistan) is performed with TecDEM and the findings indicate a high correlation between surface dynamics and basin analysis parameters with neotectonic features in the study area.

  12. DEM Simulation of Biaxial Compression Experiments of Inherently Anisotropic Granular Materials and the Boundary Effects

    Directory of Open Access Journals (Sweden)

    Zhao-Xia Tong

    2013-01-01

    Full Text Available The reliability of discrete element method (DEM numerical simulations is significantly dependent on the particle-scale parameters and boundary conditions. To verify the DEM models, two series of biaxial compression tests on ellipse-shaped steel rods are used. The comparisons on the stress-strain relationship, strength, and deformation pattern of experiments and simulations indicate that the DEM models are able to capture the key macro- and micromechanical behavior of inherently anisotropic granular materials with high fidelity. By using the validated DEM models, the boundary effects on the macrodeformation, strain localization, and nonuniformity of stress distribution inside the specimens are investigated using two rigid boundaries and one flexible boundary. The results demonstrate that the boundary condition plays a significant role on the stress-strain relationship and strength of granular materials with inherent fabric anisotropy if the stresses are calculated by the force applied on the wall. However, the responses of the particle assembly measured inside the specimens are almost the same with little influence from the boundary conditions. The peak friction angle obtained from the compression tests with flexible boundary represents the real friction angle of particle assembly. Due to the weak lateral constraints, the degree of stress nonuniformity under flexible boundary is higher than that under rigid boundary.

  13. DEM GPU studies of industrial scale particle simulations for granular flow civil engineering applications

    Science.gov (United States)

    Pizette, Patrick; Govender, Nicolin; Wilke, Daniel N.; Abriak, Nor-Edine

    2017-06-01

    The use of the Discrete Element Method (DEM) for industrial civil engineering industrial applications is currently limited due to the computational demands when large numbers of particles are considered. The graphics processing unit (GPU) with its highly parallelized hardware architecture shows potential to enable solution of civil engineering problems using discrete granular approaches. We demonstrate in this study the pratical utility of a validated GPU-enabled DEM modeling environment to simulate industrial scale granular problems. As illustration, the flow discharge of storage silos using 8 and 17 million particles is considered. DEM simulations have been performed to investigate the influence of particle size (equivalent size for the 20/40-mesh gravel) and induced shear stress for two hopper shapes. The preliminary results indicate that the shape of the hopper significantly influences the discharge rates for the same material. Specifically, this work shows that GPU-enabled DEM modeling environments can model industrial scale problems on a single portable computer within a day for 30 seconds of process time.

  14. Discrete element modelling (DEM) input parameters: understanding their impact on model predictions using statistical analysis

    Science.gov (United States)

    Yan, Z.; Wilkinson, S. K.; Stitt, E. H.; Marigo, M.

    2015-09-01

    Selection or calibration of particle property input parameters is one of the key problematic aspects for the implementation of the discrete element method (DEM). In the current study, a parametric multi-level sensitivity method is employed to understand the impact of the DEM input particle properties on the bulk responses for a given simple system: discharge of particles from a flat bottom cylindrical container onto a plate. In this case study, particle properties, such as Young's modulus, friction parameters and coefficient of restitution were systematically changed in order to assess their effect on material repose angles and particle flow rate (FR). It was shown that inter-particle static friction plays a primary role in determining both final angle of repose and FR, followed by the role of inter-particle rolling friction coefficient. The particle restitution coefficient and Young's modulus were found to have insignificant impacts and were strongly cross correlated. The proposed approach provides a systematic method that can be used to show the importance of specific DEM input parameters for a given system and then potentially facilitates their selection or calibration. It is concluded that shortening the process for input parameters selection and calibration can help in the implementation of DEM.

  15. Simulation of dilute pneumatic conveying with different types of bends by CFD-DEM

    Science.gov (United States)

    Du, J.; Hu, G. M.; Fang, Z. Q.; Wang, J.

    2014-03-01

    Bends are one of the most commonly used facilities to change flow direction in pneumatic conveying. It is important to understand the effect of the bend to the gas-solid flow structures in a pneumatic conveying system. CFD-DEM is one of powerful methods to study the fundamentals of gas-solid flow, as it takes the particle-particle and particle-wall collisions into account. But the time consumption is one of major limitations for its application. In this paper, a three-dimensional CFD-DEM model which ignores the effect of void fraction to the gas phase is used to simulate the dilute gas-solid flow. Gas-solid flows in different types of bends including horizontal-vertical, vertical-horizontal and horizontal-horizontal 90° bends are studied. The present CFD-DEM model is verified by compared the rope structure with the result for traditional CFD-DEM model in horizontal-vertical case. Compared the particle rope dispersion in different types of bends, the rope disperses more quickly in the vertical-horizontal case than others, and the solid flow structure is the most complicated in the horizontal- horizontal case. As their various solid flow structures, the collision data of three cases also seem different.

  16. Constitutive relations of dense granulates with friction and adhesion from DEM

    NARCIS (Netherlands)

    Luding, Stefan; Oñate, E.; Owen, D.R.J

    2009-01-01

    Granular materials in a split-bottom ring shear cell geometry show wide shear bands under slow, quasi-static deformation. From discrete element simulations (DEM), continuum fields like the deformation gradient and stress can be computed with the goal to formulate objective constitutive relations for

  17. DEM GPU studies of industrial scale particle simulations for granular flow civil engineering applications

    Directory of Open Access Journals (Sweden)

    Pizette Patrick

    2017-01-01

    Full Text Available The use of the Discrete Element Method (DEM for industrial civil engineering industrial applications is currently limited due to the computational demands when large numbers of particles are considered. The graphics processing unit (GPU with its highly parallelized hardware architecture shows potential to enable solution of civil engineering problems using discrete granular approaches. We demonstrate in this study the pratical utility of a validated GPU-enabled DEM modeling environment to simulate industrial scale granular problems. As illustration, the flow discharge of storage silos using 8 and 17 million particles is considered. DEM simulations have been performed to investigate the influence of particle size (equivalent size for the 20/40-mesh gravel and induced shear stress for two hopper shapes. The preliminary results indicate that the shape of the hopper significantly influences the discharge rates for the same material. Specifically, this work shows that GPU-enabled DEM modeling environments can model industrial scale problems on a single portable computer within a day for 30 seconds of process time.

  18. Kinematic behaviour of a large earthflow defined by surface displacement monitoring, DEM differencing, and ERT imaging

    Czech Academy of Sciences Publication Activity Database

    Prokešová, R.; Kardoš, M.; Tábořík, Petr; Medveďová, A.; Stacke, V.; Chudý, F.

    2014-01-01

    Roč. 224, NOV 1 (2014), s. 86-101 ISSN 0169-555X R&D Projects: GA MŠk LM2010008 Institutional support: RVO:67985891 Keywords : earthflow * surface displacement * strain modelling * DEM differencing * kinematic behaviour Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.577, year: 2013

  19. Landsat 5 TM images and DEM in lithologic mapping of Payen Volcanic Field (Mendoza Province, Argentina)

    International Nuclear Information System (INIS)

    Fornaciai, A.; Bisson, M.; Mazzarini, F.; Del Carlo, P.; Pasquare, G.

    2009-01-01

    Satellite image such as Landsat 5 TM scene provides excellent representation of Earth and synoptic view of large geographic areas in different band combination. Landsat TM images allow automatic and semi-automatic classification of land cover, nevertheless the software frequently may some difficulties in distinguishing between similar radiometric surfaces. In this case, the use of Digital Elevation Model (DEM) can be an important tool to identify different surface covers. In this study, several False Color Composite (FCC) of Landsat 5 TM Image, DEM and the respective draped image of them, were used to delineate lithological boundaries and tectonic features of regional significance of the Paven Volcanic Field (PVF). PFV is a Quaternary fissural structure belonging to the black-arc extensional areas of the Andes in the Mendoza Province (Argentina) characterized by many composite basaltic lava flow fields. The necessity to identify different lava flows with the same composition, and then with same spectral features, allows to highlight the improvement of synergic use of TM images and shaded DEM in the visual interpretation. Information obtained from Satellite data and DEM have been compared with previous geological maps and transferred into a topographical base map. Based on these data a new lithological map at 1:100.000 scale has been presented [it

  20. An Optimal DEM Reconstruction Method for Linear Array Synthetic Aperture Radar Based on Variational Model

    Directory of Open Access Journals (Sweden)

    Shi Jun

    2015-02-01

    Full Text Available Downward-looking Linear Array Synthetic Aperture Radar (LASAR has many potential applications in the topographic mapping, disaster monitoring and reconnaissance applications, especially in the mountainous area. However, limited by the sizes of platforms, its resolution in the linear array direction is always far lower than those in the range and azimuth directions. This disadvantage leads to the blurring of Three-Dimensional (3D images in the linear array direction, and restricts the application of LASAR. To date, the research on 3D SAR image enhancement has focused on the sparse recovery technique. In this case, the one-to-one mapping of Digital Elevation Model (DEM brakes down. To overcome this, an optimal DEM reconstruction method for LASAR based on the variational model is discussed in an effort to optimize the DEM and the associated scattering coefficient map, and to minimize the Mean Square Error (MSE. Using simulation experiments, it is found that the variational model is more suitable for DEM enhancement applications to all kinds of terrains compared with the Orthogonal Matching Pursuit (OMPand Least Absolute Shrinkage and Selection Operator (LASSO methods.

  1. DEM-based Watershed Delineation - Comparison of Different Methods and applications

    Science.gov (United States)

    Chu, X.; Zhang, J.; Tahmasebi Nasab, M.

    2015-12-01

    Digital elevation models (DEMs) are commonly used for large-scale watershed hydrologic and water quality modeling. With aid of the latest LiDAR technology, submeter scale DEM data are often available for many areas in the United States. Precise characterization of the detailed variations in surface microtopography using such high-resolution DEMs is crucial to the related watershed modeling. Various methods have been developed to delineate a watershed, including determination of flow directions and accumulations, identification of subbasin boundaries, and calculation of the relevant topographic parameters. The objective of this study is to examine different DEM-based watershed delineation methods by comparing their unique features and the discrepancies in their results. Not only does this study cover the traditional watershed delineation methods, but also a new puddle-based unit (PBU) delineation method. The specific topics and issues to be presented involve flow directions (D8 single flow direction vs. multi-direction methods), segmentation of stream channels, drainage systems (single "depressionless" drainage network vs. hierarchical depression-dominated drainage system), and hydrologic connectivity (static structural connectivity vs. dynamic functional connectivity). A variety of real topographic surfaces are selected and delineated by using the selected methods. Comparisons of their delineation results emphasize the importance of selection of the methods and highlight their applicability and potential impacts on watershed modeling.

  2. A problem-oriented approach for DEM data management and manipulation

    Science.gov (United States)

    Huang, Fengru; Fang, Yu; Chen, Bin

    2009-10-01

    For the last decades, GIS software technologies have made tremendous development and applied to many special fields when their targets are relevant to geographical locations. But the basis of cartographic mapping of GIS is a restriction for more development in GIS data modelling, storage and manipulation. Recently, much attention is being paid on ORDBMS(Object Relational Database Management System) to represent and manage GIS Data. New approaches have earned acceptance in many research communities and several proposals have emerged in commercial software for solving the management and manipulation on GIS vector data. Though the storage and management of field-based model data(e.g. raster, DEM, TIN) have got less achievement and people still use files and procedural ways to manipulation field-based GIS data in common applications. In this paper a new structure model using ORDBMS technology for field-based data's storage and management was proposed on the basis of full discussion on several GIS data management technologies, then a problem-oriented approach for DEM data management and manipulation was designed and implemented through open source software systems PostgreSQL and Python language. Experimental examples of different DEM data souces were stored, managed and used by using the extended spatial database system. The experiments illustrated that this solution would be a useful supplement to spatial database and it provided an effective way to DEM data management and analysis, and support the interoperability between vector data and field data.

  3. Estimating Horizontal Displacement between DEMs by Means of Particle Image Velocimetry Techniques

    Directory of Open Access Journals (Sweden)

    Juan F. Reinoso

    2015-12-01

    Full Text Available To date, digital terrain model (DTM accuracy has been studied almost exclusively by computing its height variable. However, the largely ignored horizontal component bears a great influence on the positional accuracy of certain linear features, e.g., in hydrological features. In an effort to fill this gap, we propose a means of measurement different from the geomatic approach, involving fluid mechanics (water and air flows or aerodynamics. The particle image velocimetry (PIV algorithm is proposed as an estimator of horizontal differences between digital elevation models (DEM in grid format. After applying a scale factor to the displacement estimated by the PIV algorithm, the mean error predicted is around one-seventh of the cell size of the DEM with the greatest spatial resolution, and around one-nineteenth of the cell size of the DEM with the least spatial resolution. Our methodology allows all kinds of DTMs to be compared once they are transformed into DEM format, while also allowing comparison of data from diverse capture methods, i.e., LiDAR versus photogrammetric data sources.

  4. Accuracy of Cartosat-1 DEM and its derived attribute at multiple ...

    Indian Academy of Sciences (India)

    Accuracy of Cartosat-1 DEM and its derived attribute at multiple scale representation. Samadrita Mukherjee1, Sandip Mukherjee2,∗. , A Bhardwaj1,. Anirban Mukhopadhyay3, R D Garg4 and S Hazra3. 1Indian Institute of Remote Sensing, Indian Space Research Organisation, Dehradun 248 001, India. 2Department of ...

  5. Research of the gas-solid flow character based on the DEM method

    Science.gov (United States)

    Wang, Xueyao; Xiao, Yunhan

    2011-12-01

    Numerical simulation of gas-solid flow behaviors in a rectangular fluidized bed is carried out three dimensionally by the discrete element method (DEM). Euler method and Lagrange method are employed to deal with the gas phase and solid phase respectively. The collided force among particles, striking force between particle and wall, drag force, gravity, Magnus lift force and Saffman lift force are considered when establishing the mathematic models. Soft-sphere model is used to describe the collision of particles. In addition, the Euler method is also used for modeling the solid phase to compare with the results of DEM. The flow patterns, particle mean velocities, particles' diffusion and pressure drop of the bed under typical operating conditions are obtained. The results show that the DEM method can describe the detailed information among particles, while the Euler-Euler method cannot capture the micro-scale character. No matter which method is used, the diffusion of particles increases with the increase of gas velocity. But the gathering and crushing of particles cannot be simulated, so the energy loss of particles' collision cannot be calculated and the diffusion by using the Euler-Euler method is larger. In addition, it is shown by DEM method, with strengthening of the carrying capacity, more and more particles can be schlepped upward and the dense suspension upflow pattern can be formed. However, the results given by the Euler-Euler method are not consistent with the real situation.

  6. Ueber von Hominiden bearbeitete Knochenfunde aus dem oberen Villafranchien in den Niederlanden

    NARCIS (Netherlands)

    Lüttschwager, Joh.; Bemmel, van A.C.V.

    1962-01-01

    Die Funde von Vertebratenknochen in dem Ton von Tegelen bei Venlo (Provinz Zuid Limburg, Niederlande), sind schon lange bekannt und eingehend bearbeitet worden (SCHREUDER, 1945). Die dunkelbraunen, meist gut erhaltenen Knochen, liegen im blauen Ton eingebettet. Ohne Zweifel sind die Reste einst vom

  7. Flow Dynamics of green sand in the DISAMATIC moulding process using Discrete element method (DEM)

    DEFF Research Database (Denmark)

    Hovad, Emil; Larsen, P.; Walther, Jens Honore

    2015-01-01

    to emulate some of these important conditions found in the real moulding process. The sand flow is simulated with the DEM and compared with corresponding video footages from the interior of the chamber during the moulding process. The effect of the rolling resistance and the static friction coefficient...

  8. Deep Convolutional Generative Adversarial Network for Procedural 3D Landscape Generation Based on DEM

    DEFF Research Database (Denmark)

    Wulff-Jensen, Andreas; Rant, Niclas Nerup; Møller, Tobias Nordvig

    2018-01-01

    This paper proposes a novel framework for improving procedural generation of 3D landscapes using machine learning. We utilized a Deep Convolutional Generative Adversarial Network (DC-GAN) to generate heightmaps. The network was trained on a dataset consisting of Digital Elevation Maps (DEM...

  9. Demência na doença de Parkinson Dementia in Parkinsn's disease

    Directory of Open Access Journals (Sweden)

    Leonardo Caixeta

    2008-12-01

    Full Text Available OBJETIVO: A presença de síndromes psiquiátricas, incluindo demência, associada a distúrbios motores tem sido cada vez mais reconhecida durante a última década, com destaque para o prejuízo cognitivo na doença de Parkinson idiopática. Esta revisão enfocará a epidemiologia, os aspectos clínicos, diagnósticos diferenciais, mecanismos subjacentes e o tratamento da demência na doença de Parkinson idiopática. MÉTODO: Uma revisão da literatura dos estudos que investigaram a demência da doença de Parkinson idiopática foi realizada. RESULTADOS: A demência é altamente prevalente na doença de Parkinson idiopática. O protótipo da demência na doença de Parkinson idiopática consiste numa síndrome disexecutiva com comprometimento da atenção, funções executivas e, secundariamente, a memória. Neuroquimicamente, o déficit mais significativo parece ser colinérgico; a demência se correlaciona com a presença de corpos de Lewy corticais e límbicos. Evidências preliminares sugerem que os anticolinesterásicos podem ser efetivos na demência da doença de Parkinson idiopática. CONCLUSÕES: O prejuízo cognitivo na doença de Parkinson idiopática é associado a características próprias e é responsável por importante incapacidade nestes pacientes.OBJECTIVE: The concomitant presence of psychiatric syndromes, including dementia, with motor disturbance has been increasingly recognized during the last decade, with emphasis on cognitive impairment in idiopatic Parkinson's disease. This review will focus on the epidemiology, clinical aspects, differential diagnosis, underlying mechanisms and treatment of dementia in Parkinson's disease. METHOD: A literature review of the studies that investigated the dementia in Parkinson's disease was performed. RESULTS: Dementia is highly prevalent in Parkinson's disease. The prototype of dementia in Parkinson's disease is a dysexecutive syndrome with impaired attention, executive functions and

  10. Effect of DEM resolution and comparison between different weighting factors for hydrologic connectivity index

    Science.gov (United States)

    Cantreul, Vincent; Cavalli, Marco; Degré, Aurore

    2016-04-01

    The emerging concept of hydrological connectivity is difficult to quantify. Some indices have been proposed. The most cited is Borselli's one. It mainly uses the DEM as input. The pixel size may strongly impacts the result of the calculation. It has not been studied yet in silty areas. Another important aspect is the choice of the weighting factor which strongly influences the index value. The objective of this poster is so to compare 8 different DEM's resolutions (12, 24, 48, 72, 96, 204, 504 and 996cm) and 3 different weighting factors (factor C of Wischmeier, Manning's factor and rugosity index) in the Borselli's index calculation. The IC was calculated in a 124ha catchment (Hevillers), in the loess belt, in Belgium. The DEM used is coming from a UAV with a maximum resolution of 12 cm. Permanent covered surfaces are not considered in order to avoid artefact due to the vegetation (2% of the surface). Regarding the DEM pixel size, the IC increases for a given pixel when the pixel size decreases. That confirms some results observed in the Alpine region by Cavalli (2014). The mean difference between 12 cm and 10 m resolution is 35% with higher values up to 100% for higher connectivity zones (flow paths). Another result is the lower impact of connections in the watershed (grass strips…) at lower pixel sizes. This is linked to the small width of some connections which are sometimes comparing to cell size. Furthermore, a great loss of precision is observed from the 500 cm pixel size and upper. That remark is quite intuitive. Finally, some very well disconnected zones appear for the highest resolutions. Regarding the weighting factor, IC values calculated using C factor are lower than with the rugosity index which is only a topographic factor. With very high resolution DEM, it permits to represent the fine topography. For the C factor, the zones up to very well disconnected areas (grass strips, wood…) are well represented with lower index values than downstream

  11. Three-dimensional simulation of a solid-liquid flow by the DEM-SPH method

    Science.gov (United States)

    Sun, Xiaosong; Sakai, Mikio; Yamada, Yoshinori

    2013-09-01

    In this paper, we describe a new Lagrangian-Lagrangian algorithm, which is referred to be the DEM-SPH method, for solid-liquid flows involving free surfaces. The DEM solid phase and the SPH liquid phase are coupled using the local averaging technique described by Lagrangian approaches, where both the continuity equation and the interaction force, i.e. drag force, are connected with the local mean voidage. Conservative forms of momentum transformation are derived for the DEM-SPH interaction via a variational approach. By introducing a correction to the SPH approximation with explicit inclusion of boundary information, arbitrary boundaries can be modeled without any extra wall particles, where the boundary is used commonly for both DEM and SPH phases. We deploy level-set distance functions to efficiently construct and evaluate this boundary model. To examine the validity of the present method, we perform three-dimensional simulations of a dynamic flow in a solid-liquid dam break and a quasi-steady flow in a rotating cylindrical tank; and we conduct validation experiments to justify the simulation results. In the dam-break problem, positions of wave fronts during the collapse are computed and compared with experimental measurements; for the circulating tank, some macroscopic aspects of the steady flow, e.g. the shape, dimension and velocity profile of the solid bed, are obtained for validation data. In both cases, the simulation results are in good agreement with those of the experiment. Consequently, the DEM-SPH method is proved to be adequate in modeling solid-liquid flows through this study.

  12. DEM GENERATION FROM HIGH RESOLUTION SATELLITE IMAGES THROUGH A NEW 3D LEAST SQUARES MATCHING ALGORITHM

    Directory of Open Access Journals (Sweden)

    T. Kim

    2012-09-01

    Full Text Available Automated generation of digital elevation models (DEMs from high resolution satellite images (HRSIs has been an active research topic for many years. However, stereo matching of HRSIs, in particular based on image-space search, is still difficult due to occlusions and building facades within them. Object-space matching schemes, proposed to overcome these problem, often are very time consuming and critical to the dimensions of voxels. In this paper, we tried a new least square matching (LSM algorithm that works in a 3D object space. The algorithm starts with an initial height value on one location of the object space. From this 3D point, the left and right image points are projected. The true height is calculated by iterative least squares estimation based on the grey level differences between the left and right patches centred on the projected left and right points. We tested the 3D LSM to the Worldview images over 'Terrassa Sud' provided by the ISPRS WG I/4. We also compared the performance of the 3D LSM with the correlation matching based on 2D image space and the correlation matching based on 3D object space. The accuracy of the DEM from each method was analysed against the ground truth. Test results showed that 3D LSM offers more accurate DEMs over the conventional matching algorithms. Results also showed that 3D LSM is sensitive to the accuracy of initial height value to start the estimation. We combined the 3D COM and 3D LSM for accurate and robust DEM generation from HRSIs. The major contribution of this paper is that we proposed and validated that LSM can be applied to object space and that the combination of 3D correlation and 3D LSM can be a good solution for automated DEM generation from HRSIs.

  13. DemQSAR: predicting human volume of distribution and clearance of drugs

    Science.gov (United States)

    Demir-Kavuk, Ozgur; Bentzien, Jörg; Muegge, Ingo; Knapp, Ernst-Walter

    2011-12-01

    In silico methods characterizing molecular compounds with respect to pharmacologically relevant properties can accelerate the identification of new drugs and reduce their development costs. Quantitative structure-activity/-property relationship (QSAR/QSPR) correlate structure and physico-chemical properties of molecular compounds with a specific functional activity/property under study. Typically a large number of molecular features are generated for the compounds. In many cases the number of generated features exceeds the number of molecular compounds with known property values that are available for learning. Machine learning methods tend to overfit the training data in such situations, i.e. the method adjusts to very specific features of the training data, which are not characteristic for the considered property. This problem can be alleviated by diminishing the influence of unimportant, redundant or even misleading features. A better strategy is to eliminate such features completely. Ideally, a molecular property can be described by a small number of features that are chemically interpretable. The purpose of the present contribution is to provide a predictive modeling approach, which combines feature generation, feature selection, model building and control of overtraining into a single application called DemQSAR. DemQSAR is used to predict human volume of distribution (VDss) and human clearance (CL). To control overtraining, quadratic and linear regularization terms were employed. A recursive feature selection approach is used to reduce the number of descriptors. The prediction performance is as good as the best predictions reported in the recent literature. The example presented here demonstrates that DemQSAR can generate a model that uses very few features while maintaining high predictive power. A standalone DemQSAR Java application for model building of any user defined property as well as a web interface for the prediction of human VDss and CL is

  14. Assessment of neuro-optometric rehabilitation using the Developmental Eye Movement (DEM) test in adults with acquired brain injury.

    Science.gov (United States)

    Kapoor, Neera; Ciuffreda, Kenneth Joseph

    This pilot study sought to determine the efficacy of using the Developmental Eye Movement (DEM) test in the adult, acquired brain injury (ABI) population to quantify clinically the effects of controlled, laboratory-performed, oculomotor-based vision therapy/vision rehabilitation. Nine adult subjects with mild traumatic brain injury (mTBI) and five with stroke were assessed before and after an eight-week, computer-based, versional oculomotor (fixation, saccades, pursuit, and simulated reading) training program (9.6h total). The protocol incorporated a cross-over, interventional design with and without the addition of auditory feedback regarding two-dimensional eye position. The clinical outcome measure was the Developmental Eye Movement (DEM) test score (ratio, errors) taken before, midway, and immediately following training. For the DEM ratio parameter, improvements were found in 80-89% of the subjects. For the DEM error parameter, improvements were found in 100% of the subjects. Incorporation of the auditory feedback component revealed a trend toward enhanced performance. The findings were similar for both DEM parameters, as well as for incorporation of the auditory feedback, in both diagnostic groups. The results of the present study demonstrated considerable improvements in the DEM test scores following the oculomotor-based training, thus reflecting more time-optimal and accurate saccadic tracking after the training. The DEM test should be considered as another clinical test of global saccadic tracking performance in the ABI population. Copyright © 2017 Spanish General Council of Optometry. All rights reserved.

  15. Visualising DEM-related flood-map uncertainties using a disparity-distance equation algorithm

    Directory of Open Access Journals (Sweden)

    S. A. Brandt

    2016-05-01

    Full Text Available The apparent absoluteness of information presented by crisp-delineated flood boundaries can lead to misconceptions among planners about the inherent uncertainties associated in generated flood maps. Even maps based on hydraulic modelling using the highest-resolution digital elevation models (DEMs, and calibrated with the most optimal Manning's roughness (n coefficients, are susceptible to errors when compared to actual flood boundaries, specifically in flat areas. Therefore, the inaccuracies in inundation extents, brought about by the characteristics of the slope perpendicular to the flow direction of the river, have to be accounted for. Instead of using the typical Monte Carlo simulation and probabilistic methods for uncertainty quantification, an empirical-based disparity-distance equation that considers the effects of both the DEM resolution and slope was used to create prediction-uncertainty zones around the resulting inundation extents of a one-dimensional (1-D hydraulic model. The equation was originally derived for the Eskilstuna River where flood maps, based on DEM data of different resolutions, were evaluated for the slope-disparity relationship. To assess whether the equation is applicable to another river with different characteristics, modelled inundation extents from the Testebo River were utilised and tested with the equation. By using the cross-sectional locations, water surface elevations, and DEM, uncertainty zones around the original inundation boundary line can be produced for different confidences. The results show that (1 the proposed method is useful both for estimating and directly visualising model inaccuracies caused by the combined effects of slope and DEM resolution, and (2 the DEM-related uncertainties alone do not account for the total inaccuracy of the derived flood map. Decision-makers can apply it to already existing flood maps, thereby recapitulating and re-analysing the inundation boundaries and the areas that

  16. Demência na população de pacientes do Hospital das Clínicas da Unicamp

    OpenAIRE

    Silva,David W.; Damasceno,Benito P.

    2002-01-01

    OBJETIVO: Descrever subtipos de demência em pacientes atendidos no HC-UNICAMP. METODO: No período 1989-1998, foram admitidos 261 pacientes com demência (89,7% estudados retrospectivamente, e 10,3% prospectivamente); idade 63,5 anos (±13,2) e educação 3,6 anos (±3,9; 25% analfabetos). O diagnóstico de demência e seus subtipos baseou-se no DSM-IV, CAMDEX, NINCDS-ADRDA, NINDS-AIREN/ADDTC, Lund-Manchester, tap-teste liquórico, exames laboratoriais e de neuroimagem. RESULTADOS: Sesse...

  17. Study of interactions between sediment particles in sheet flow using CFD-DEM

    Science.gov (United States)

    Sun, Rui; Xiao, Heng

    2015-11-01

    CFD-DEM simulation is a promising approach in the study of sediment transport. However, the study of sediment transport in sheet flow is still lacking. In this work, a parallelized CFD-DEM solver sediFoam, which has been extensively validated, is applied to the study of sediment transport. Numerical simulations of sediment bed of different characteristics under various waves are studied and compared with the results obtained in the literature, including sediment transport flux, solid volume fraction, and movable bed height. The micro-structures (e.g., contact network) and macroscopic solid phase stresses of the sediment bed are analyzed to gain insight into the inter-particle interactions during the transport process. Additionally, the microstructural properties and solid phase stresses in wave-induced sheet flow are compared to those obtained in unidirectional currents, and significant difference is observed.

  18. Micromechanics of non-active clays in saturated state and DEM modelling

    Science.gov (United States)

    Pagano, Arianna Gea; Tarantino, Alessandro; Pedrotti, Matteo; Magnanimo, Vanessa; Windows-Yule, Kit; Weinhart, Thomas

    2017-06-01

    The paper presents a conceptual micromechanical model for 1-D compression behaviour of non-active clays in saturated state. An experimental investigation was carried out on kaolin clay samples saturated with fluids of different pH and dielectric permittivity. The effect of pore fluid characteristics on one-dimensional compressibility behaviour of kaolin was investigated. A three dimensional Discrete Element Method (DEM) was implemented in order to simulate the response of saturated kaolin observed during the experiments. A complex contact model was introduced, considering both the mechanical and physico-chemical microscopic interactions between clay particles. A simple analysis with spherical particles only was performed as a preliminary step in the DEM study in the elastic regime.

  19. A hybrid FEM-DEM approach to the simulation of fluid flow laden with many particles

    Science.gov (United States)

    Casagrande, Marcus V. S.; Alves, José L. D.; Silva, Carlos E.; Alves, Fábio T.; Elias, Renato N.; Coutinho, Alvaro L. G. A.

    2017-04-01

    In this work we address a contribution to the study of particle laden fluid flows in scales smaller than TFM (two-fluid models). The hybrid model is based on a Lagrangian-Eulerian approach. A Lagrangian description is used for the particle system employing the discrete element method (DEM), while a fixed Eulerian mesh is used for the fluid phase modeled by the finite element method (FEM). The resulting coupled DEM-FEM model is integrated in time with a subcycling scheme. The aforementioned scheme is applied in the simulation of a seabed current to analyze which mechanisms lead to the emergence of bedload transport and sediment suspension, and also quantify the effective viscosity of the seabed in comparison with the ideal no-slip wall condition. A simulation of a salt plume falling in a fluid column is performed, comparing the main characteristics of the system with an experiment.

  20. Numerical modelling of powder caking at REV scale by using DEM

    Science.gov (United States)

    Guessasma, Mohamed; Silva Tavares, Homayra; Afrassiabian, Zahra; Saleh, Khashayar

    2017-06-01

    This work deals with numerical simulation of powder caking process caused by capillary condensation phenomenon. Caking consists in unwanted agglomeration of powder particles. This process is often irreversible and not easy to predict. To reproduce mechanism involved by caking phenomenon we have used the Discrete Elements Method (DEM). In the present work, we mainly focus on the role of capillary condensation and subsequent liquid bridge formation within a granular medium exposed to fluctuations of ambient relative humidity. Such bridges cause an attractive force between particles, leading to the formation of a cake with intrinsic physicochemical and mechanical properties. By considering a Representative Elementary Volume (REV), the DEM is then performed by means of a MULTICOR-3D software tacking into account the properties of the cake (degree of saturation) in order to establish relationships between the microscopic parameters and the macroscopic behaviour (tensile strength).

  1. DEM modelling of the penetration process of the HP3 Mole

    Science.gov (United States)

    Poganski, J.; Kargl, G.; Schweiger, H.; Kömle, N.

    2015-10-01

    The NASA InSight Mission will be launched in March 2016 and will reach the surface of Mars roughly nine months later in the Elysium Region. One of the instruments on board is the HP³ Mole to measure the planetary heat flow. For this purpose it needs to penetrate five meters deep into the surface of Mars and thus offers also the possibility to analyse the soil properties. For the reconstruction of the soil behaviour and also to predict the mole performance and maximum reachable depth in advance, numerical simulations are used. The simulation of the soil during the hammering process of the HP³ Mole requires a substantial numerical effort due to the local high dynamics and large soil deformations that occur. After comparing the capability of various simulation methods (FEM, MPM and DEM) a discrete element method (DEM) was chosen.

  2. Rechargable Lithium-Air Batteries: Investigation of Redox Mediators Using DEMS

    DEFF Research Database (Denmark)

    Christensen, Mathias Kjærgård; Storm, Mie Møller; Norby, Poul

    2016-01-01

    The rechargeable aprotic lithium-air battery is a promising technology that offers high theoretical energy density of as much 10 times the capacity of current Li-ion batteries. This type of battery technology differs from conventional batteries because of the gas exchange during discharge....../charge cycling. Characterizing the gas content during charge using Differential Electrochemical Mass Spectroscopy (DEMS) allows for in-situ characterization of chemistry in the battery. Using our DEMS setup we have investigated different cathode materials for lithium-air batteries. A carbon black cathode...... material or electrolyte is being decomposed. This is also seen with Thermally reduced Graphene Oxide (TrGO). The graphene based cathode is interesting as it exhibits a high surface area which in turn increases capacity. Using the additive LiI, functioning as a redox mediator, the discharge curve remains...

  3. Doppler Centroid Estimation for Airborne SAR Supported by POS and DEM

    Directory of Open Access Journals (Sweden)

    CHENG Chunquan

    2015-05-01

    Full Text Available It is difficult to estimate the Doppler frequency and modulating rate for airborne SAR by using traditional vector method due to instable flight and complex terrain. In this paper, it is qualitatively analyzed that the impacts of POS, DEM and their errors on airborne SAR Doppler parameters. Then an innovative vector method is presented based on the range-coplanarity equation to estimate the Doppler centroid taking the POS and DEM as auxiliary data. The effectiveness of the proposed method is validated and analyzed via the simulation experiments. The theoretical analysis and experimental results show that the method can be used to estimate the Doppler centroid with high accuracy even in the cases of high relief, instable flight, and large squint SAR.

  4. Micromechanics of non-active clays in saturated state and DEM modelling

    Directory of Open Access Journals (Sweden)

    Pagano Arianna Gea

    2017-01-01

    Full Text Available The paper presents a conceptual micromechanical model for 1-D compression behaviour of non-active clays in saturated state. An experimental investigation was carried out on kaolin clay samples saturated with fluids of different pH and dielectric permittivity. The effect of pore fluid characteristics on one-dimensional compressibility behaviour of kaolin was investigated. A three dimensional Discrete Element Method (DEM was implemented in order to simulate the response of saturated kaolin observed during the experiments. A complex contact model was introduced, considering both the mechanical and physico-chemical microscopic interactions between clay particles. A simple analysis with spherical particles only was performed as a preliminary step in the DEM study in the elastic regime.

  5. All you need is shape: Predicting shear banding in sand with LS-DEM

    Science.gov (United States)

    Kawamoto, Reid; Andò, Edward; Viggiani, Gioacchino; Andrade, José E.

    2018-02-01

    This paper presents discrete element method (DEM) simulations with experimental comparisons at multiple length scales-underscoring the crucial role of particle shape. The simulations build on technological advances in the DEM furnished by level sets (LS-DEM), which enable the mathematical representation of the surface of arbitrarily-shaped particles such as grains of sand. We show that this ability to model shape enables unprecedented capture of the mechanics of granular materials across scales ranging from macroscopic behavior to local behavior to particle behavior. Specifically, the model is able to predict the onset and evolution of shear banding in sands, replicating the most advanced high-fidelity experiments in triaxial compression equipped with sequential X-ray tomography imaging. We present comparisons of the model and experiment at an unprecedented level of quantitative agreement-building a one-to-one model where every particle in the more than 53,000-particle array has its own avatar or numerical twin. Furthermore, the boundary conditions of the experiment are faithfully captured by modeling the membrane effect as well as the platen displacement and tilting. The results show a computational tool that can give insight into the physics and mechanics of granular materials undergoing shear deformation and failure, with computational times comparable to those of the experiment. One quantitative measure that is extracted from the LS-DEM simulations that is currently not available experimentally is the evolution of three dimensional force chains inside and outside of the shear band. We show that the rotations on the force chains are correlated to the rotations in stress principal directions.

  6. Das Problem der sogenannten zusammengesetzten Bezirke auf dem Balkan im 11. Jahrhundert: Zwei fallbeispiele

    Directory of Open Access Journals (Sweden)

    Krsmanović Bojana

    2009-01-01

    Full Text Available (nemački In der vorliegenden Arbeit wurden Charakteristika der sogenannten zusammengesetzten militärisch-zivilen Bezirke behandelt, die aus zwei oder drei Untereinheiten bestanden. Diese Untereinheiten der zusammengesetzten Bezirke hatten in der Regel feste zivile und militärische Verwaltungsstrukturen, d.h. sie hatten eine gewisse Unabhängigkeit. Ein zusammengesetzter Bezirk konnte in den Quellen als ein 'thema' (im Singular bezeichnet werden oder auch im Plural als 'themata'. An seiner Spitze befand sich ein Dux/katepano oder gelegentlich auch ein Stratege. Der zivilen Verwaltung stand ein Richter/Prätor vor, welcher häufig das Amt eines anagrapheus innehatte. Weiterhin wurde der zusammengesetzte Bezirk Voleron-Strymon-Thessalonike naher untersucht sowie die Probleme, die mit dem Status seiner Unterheiten, insbesondere mit Voleron, zusammenhängen. Es ist möglich, dass aus denjenigen Gebieten des Balkans, die nach dem Jahr 1018 unter byzantinische Herrschaft gefallen waren, ein zusammengesetzter Bezirk gebildet wurde. Die Rede ist von dem Thema Bulgaria-Sirmium-Paradounavon. Es wird vermutet, dass die demographischen Umstände sowie die ethnische Zusammensetzung der Bevölkerung der Region Einfluss auf die Charakteristika des zusammengesetzten Bezirks hatten. Die zivile Verwaltungsstruktur war hier nicht derart beständig wie in den anderen Gebieten des Balkans, die bereits vor dem Krieg von 976-1018 unter byzantinischer Herrschaft standen. Sirmium und Paradounavon scheinen im zivilen Bereich der Verwaltung von Amtsträgern aus Bulgarien geleitet worden zu sein, wahrend die militärische Führung anscheinend unabhängig von Bulgarien war.

  7. Performance Prediction and Verification for the Synchronization Link of TanDEM-X

    OpenAIRE

    Younis, Marwan; Metzig, Robert; Krieger, Gerhard; Bachmann, Markus; Klein, Rainer

    2007-01-01

    Bistatic Synthetic Aperture Radar (SAR) systems have a high potential for scientific, commercial and security applications. One of the benefits is the possibility to generate digital elevation models using bistatic interferometry. A bistatic satellite mission with interferometric capabilities is TanDEM-X, which consists of two nearly identical SAR satellites. The first, TerraSAR-X, will be launched in February 2007, while the second is currently in Phase-C. The fact that both radar instrument...

  8. a Hadoop-Based Algorithm of Generating dem Grid from Point Cloud Data

    Science.gov (United States)

    Jian, X.; Xiao, X.; Chengfang, H.; Zhizhong, Z.; Zhaohui, W.; Dengzhong, Z.

    2015-04-01

    Airborne LiDAR technology has proven to be the most powerful tools to obtain high-density, high-accuracy and significantly detailed surface information of terrain and surface objects within a short time, and from which the Digital Elevation Model of high quality can be extracted. Point cloud data generated from the pre-processed data should be classified by segmentation algorithms, so as to differ the terrain points from disorganized points, then followed by a procedure of interpolating the selected points to turn points into DEM data. The whole procedure takes a long time and huge computing resource due to high-density, that is concentrated on by a number of researches. Hadoop is a distributed system infrastructure developed by the Apache Foundation, which contains a highly fault-tolerant distributed file system (HDFS) with high transmission rate and a parallel programming model (Map/Reduce). Such a framework is appropriate for DEM generation algorithms to improve efficiency. Point cloud data of Dongting Lake acquired by Riegl LMS-Q680i laser scanner was utilized as the original data to generate DEM by a Hadoop-based algorithms implemented in Linux, then followed by another traditional procedure programmed by C++ as the comparative experiment. Then the algorithm's efficiency, coding complexity, and performance-cost ratio were discussed for the comparison. The results demonstrate that the algorithm's speed depends on size of point set and density of DEM grid, and the non-Hadoop implementation can achieve a high performance when memory is big enough, but the multiple Hadoop implementation can achieve a higher performance-cost ratio, while point set is of vast quantities on the other hand.

  9. Tratamento dos transtornos do comportamento de pacientes com demência

    Directory of Open Access Journals (Sweden)

    Tamai Sérgio

    2002-01-01

    Full Text Available No curso da demência, transtornos não-cognitivos comportamentais são altamente prevalentes. Esses sintomas psicológicos e comportamentais da demência (SPCD são mais importantes no dia-a-dia do que os déficits cognitivos, tanto para o paciente quanto para o cuidador, em termos de angústia e incapacitação causadas. Os SPCD freqüentemente levam à institucionalização. O raciocínio para o uso de drogas psicotrópicas está parcialmente baseado nas semelhanças fenomenológicas entre alguns comportamentos observados em pacientes idosos dementados e sinais e sintomas de transtornos psiquiátricos, como os transtornos depressivos, psicóticos ou ansiosos, em pacientes não-dementados. Na realidade, os SPCD são, com freqüência, qualitativamente diferentes daqueles que caracterizam os transtornos psicóticos, depressivos ou ansiosos. Os estudos de seguimento de tratamento sugerem que as drogas antipsicóticas são menos eficazes em pacientes com doença de Alzheimer ou demência de lobo frontal do que em pacientes com transtornos psiquiátricos. Abordagens não-farmacológicas são a primeira escolha no tratamento dos SPCD. Os inibidores da colinesterase no tratamento dos SPCD na doença de Alzheimer e na demência cortical difusa por corpos de Lewi representam uma abordagem terapêutica promissora.

  10. DEM Simulations of Granular Secondary Flow in Cylindrical Vertical Bladed Mixer – Effect of Blade Rake.

    OpenAIRE

    Trávníčková, T. (Tereza); Havlica, J. (Jaromír); Kohout, M.

    2016-01-01

    Mixing of granular systems is one of the most used chemical engineering unit operations. However, detailed description of the dynamics of granular flows through experiments is difficult. Therefore, usage of mathematical modeling increases. In this paper we deal with DEM (Discreet Element Method) simulations of mixing glass beads in a cylindrical vertical bladed mixer. The aim of this work is to describe the influence of blade rake on the development of granular secondary flows for different s...

  11. CFD-DEM Onset of Motion Analysis for Application to Bed Scour Risk Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-03-01

    This CFD study with DEM was done as a part of the Federal Highway Administration’s (FHWA’s) effort to improve scour design procedures. The Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model, available in CD-Adapco’s StarCCM+ software, was used to simulate multiphase systems, mainly those which combine fluids and solids. In this method the motion of discrete solids is accounted for by DEM, which applies Newton's laws of motion to every particle. The flow of the fluid is determined by the local averaged Navier–Stokes equations that can be solved using the traditional CFD approach. The interactions between the fluid phase and solids phase are modeled by use of Newton's third law. The inter-particle contact forces are included in the equations of motion. Soft-particle formulation is used, which allows particles to overlap. In this study DEM was used to model separate sediment grains and spherical particles laying on the bed with the aim to analyze their movement due to flow conditions. Critical shear stress causing the incipient movement of the sediment was established and compared to the available experimental data. An example of scour around a cylindrical pier is considered. Various depths of the scoured bed and flow conditions were taken into account to gain a better understanding of the erosion forces existing around bridge foundations. The decay of these forces with increasing scour depth was quantified with a ‘decay function’, which shows that particles become increasingly less likely to be set in motion by flow forces as a scour hole increases in depth. Computational and experimental examples of the scoured bed around a cylindrical pier are presented.

  12. Applying DEM-SRTM for reconstructing a late Quaternary paleodrainage in Amazonia

    Science.gov (United States)

    Hayakawa, Ericson H.; Rossetti, Dilce F.; Valeriano, Márcio M.

    2010-08-01

    Remote sensing is a particularly invaluable tool that has helped the detection of paleomorphologies produced by river dislocation in a variety of landscapes, which has contributed in reconstructing the geological evolution of many fluvial systems. This technique might provide useful information to discuss the evolution of large fluvial systems, in special those located in areas of difficult access where the acquisition of field data is difficult. Application of remote sensing for paleodrainage characterization in densely vegetated tropical areas is scarce in the literature. This work records processing of the Digital Elevation Model (DEM) derived from the Shuttle Radar Topography Mission (SRTM), which succeeded in revealing an ancient drainage complex of the Madeira River, one of the main Amazonas tributaries, where other remote sensing products failed the detection. Analysis of this paleodrainage and of its modern counterpart within the geological framework available for this region leads to propose that activity along pre-existent faults during the latest Quaternary would have promoted the southeastward dislocation of a nearly 200 km long segment of the Madeira River. During this process, an impressive paleodrainage network was left behind, which was only able to be detected using the DEM-SRTM. Application of this technique might be of great help to the detection of paleodrainage morphologies in densely vegetated areas similar to the Amazonas lowland. The dynamics of channel migration in this and many other large scale tropical river systems might benefit from the investigation based on data derived from DEM-SRTM.

  13. Dissipation consistent fabric tensor definition from DEM to continuum for granular media

    Science.gov (United States)

    Li, X. S.; Dafalias, Y. F.

    2015-05-01

    In elastoplastic soil models aimed at capturing the impact of fabric anisotropy, a necessary ingredient is a measure of anisotropic fabric in the form of an evolving tensor. While it is possible to formulate such a fabric tensor based on indirect phenomenological observations at the continuum level, it is more effective and insightful to have the tensor defined first based on direct particle level microstructural observations and subsequently deduce a corresponding continuum definition. A practical means able to provide such observations, at least in the context of fabric evolution mechanisms, is the discrete element method (DEM). Some DEM defined fabric tensors such as the one based on the statistics of interparticle contact normals have already gained widespread acceptance as a quantitative measure of fabric anisotropy among researchers of granular material behavior. On the other hand, a fabric tensor in continuum elastoplastic modeling has been treated as a tensor-valued internal variable whose evolution must be properly linked to physical dissipation. Accordingly, the adaptation of a DEM fabric tensor definition to a continuum constitutive modeling theory must be thermodynamically consistent in regards to dissipation mechanisms. The present paper addresses this issue in detail, brings up possible pitfalls if such consistency is violated and proposes remedies and guidelines for such adaptation within a recently developed Anisotropic Critical State Theory (ACST) for granular materials.

  14. Parametrisation of a DEM model for railway ballast under different load cases.

    Science.gov (United States)

    Suhr, Bettina; Six, Klaus

    2017-01-01

    The prediction quality of discrete element method (DEM) models for railway ballast can be expected to depend on three points: the geometry representation of the single particles, the used contact models and the parametrisation using principal experiments. This works aims at a balanced approach, where none of the points is addressed with excessive depth. In a first step, a simple geometry representation is chosen and the simplified Hertz-Mindlin contact model is used. When experimental data of cyclic compression tests and monotonic direct shear tests are considered, the model can be parametrised to fit either one of the two tests, but not both with the same set of parameters. Similar problems can be found in literature for monotonic and cyclic triaxial tests of railway ballast. In this work, the comparison between experiment and simulation is conducted using the entire data of the test, e.g. shear force over shear path curve from the direct shear test. In addition to a visual comparison of the results also quantitative errors based on the sum of squares are defined. To improve the fit of the DEM model to both types of experiments, an extension on the Hertz-Mindlin contact law is used, which introduces additional physical effects (e.g. breakage of edges or yielding). This model introduces two extra material parameters and is successfully parametrised. Using only one set of parameters, the results of the DEM simulation are in good accordance with both experimental cyclic compression test and monotonic directs shear test.

  15. Compressibility and tablet forming ability of bimodal granule mixtures: Experiments and DEM simulations.

    Science.gov (United States)

    Nordström, Josefina; Alderborn, Göran; Frenning, Göran

    2018-04-05

    Compressibility and tablet forming ability (compactibility) of bimodal mixtures of differently sized granules formed from microcrystalline cellulose were studied experimentally and numerically with the discrete element method (DEM). Compression data was analysed using the Kawakita equation. A multi-body contact law that accounts for contact dependence resulting from plastic incompressibility/geometric hardening was used in the DEM simulations. The experimental Kawakita a and 1/b parameters both depended non-monotonically on composition (weight fraction of large particles). For the a parameter, this dependence was explained by variations in the porosity of the initial granule beds; for the 1/b parameter, other factors were found to be of importance as well. The numerical results generally compared favourably with the experiments, demonstrating the usefulness of the DEM at high relative densities, provided that a suitable multi-particle contact model is used. For all mixtures, the tensile strength of the formed tablets increased with increasing applied pressure. The tensile strength generally decreased with increasing fraction of large particle, and this decrease was more rapid for large differences in particle size. A possible interpretation of these findings was proposed, in terms of differences in lateral support of small particles in the vicinity of large particles. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. DEM Modelling of Granule Rearrangement and Fracture Behaviours During a Closed-Die Compaction.

    Science.gov (United States)

    Furukawa, Ryoichi; Kadota, Kazunori; Noguchi, Tetsuro; Shimosaka, Atsuko; Shirakawa, Yoshiyuki

    2017-08-01

    The closed-die compaction behaviour of D-mannitol granules has been simulated by the discrete element method (DEM) to investigate the granule rearrangement and fracture behaviour during compaction which affects the compactibility of the tablet. The D-mannitol granules produced in a fluidized bed were modelled as agglomerates of primary particles connected by linear spring bonds. The validity of the model granule used in the DEM simulation was demonstrated by comparing to the experimental results of a uniaxial compression test. During uniaxial compression, the numerical results of the force-displacement curve corresponded reasonably well to the experimental data. The closed-die compaction of the modelled granules was carried out to investigate the rearrangement and fracture behaviours of the granule at different upper platen velocities. The forces during closed-die compaction calculated by DEM fluctuated in the low-pressure region due to the rearrangement of granules. A Heckel analysis showed that the force fluctuation occurred at the initial bending region of the Heckel plot, which represents the granule rearrangement and fracture. Furthermore, the upper platen velocity affected the trend of compaction forces, which can lead to compaction failure due to capping. These results could contribute to designing the appropriate granules during closed-die compaction.

  17. A coupled FVM-DEM method to simulate internal erosion process in micro scale granular system

    Science.gov (United States)

    Feng, Q.; Man, T.; Hill, K. M.; Fu, X.

    2017-12-01

    This work presents a three dimensional coupling DEM-FVM method to simulate and analyze internal erosion behavior in a micro-scale granular system. The FVM (Finite Volume Method) part is set to simulate the seepage flow through the simulation field, providing the spatial distribution of fluid conditions (e.g., water discharge and confining pressure). The DEM (Discrete Element Method) part helps reproduce the details, such as the location, movement and rotation of soil particles driven by the resolved flow, and update the parameters used in the FVM part (e.g., porosity and grain size gradation). The simulation result is proved to be stable and reliable by verified convergence and symmetry in velocity profile as well as by reproduced rheology rules of granular flow. Then a series of cases with different boundary conditions were simulated. The value of critical shear stress, which is an essential parameter in macroscopic modeling framework, was statistically drawn within the granular system. It was shown that the value of critical shear stress remains a constant under given soil gradation and normal pressure, no matter how the hydraulic gradient changes. This finding is consistent with traditional assumption of being constant and shows the capability of reproducing macroscopic properties of soil through using the FVM-DEM modeling approach.

  18. A Review of Discrete Element Method (DEM) Particle Shapes and Size Distributions for Lunar Soil

    Science.gov (United States)

    Lane, John E.; Metzger, Philip T.; Wilkinson, R. Allen

    2010-01-01

    As part of ongoing efforts to develop models of lunar soil mechanics, this report reviews two topics that are important to discrete element method (DEM) modeling the behavior of soils (such as lunar soils): (1) methods of modeling particle shapes and (2) analytical representations of particle size distribution. The choice of particle shape complexity is driven primarily by opposing tradeoffs with total number of particles, computer memory, and total simulation computer processing time. The choice is also dependent on available DEM software capabilities. For example, PFC2D/PFC3D and EDEM support clustering of spheres; MIMES incorporates superquadric particle shapes; and BLOKS3D provides polyhedra shapes. Most commercial and custom DEM software supports some type of complex particle shape beyond the standard sphere. Convex polyhedra, clusters of spheres and single parametric particle shapes such as the ellipsoid, polyellipsoid, and superquadric, are all motivated by the desire to introduce asymmetry into the particle shape, as well as edges and corners, in order to better simulate actual granular particle shapes and behavior. An empirical particle size distribution (PSD) formula is shown to fit desert sand data from Bagnold. Particle size data of JSC-1a obtained from a fine particle analyzer at the NASA Kennedy Space Center is also fitted to a similar empirical PSD function.

  19. Investigation of the fluidized bed-chemical vapor deposition (FBCVD) process using CFD-DEM method

    International Nuclear Information System (INIS)

    Liu Malin; Liu Rongzheng; Wen Yuanyun; Liu Bing; Shao Youlin

    2014-01-01

    The CFD-DEM-CVD multiscale coupling simulation concept was proposed based on the mass/momentum/energy transfer involved in the FB-CVD process. The pyrolysis process of the reaction gas in the spouted bed can be simulated by CFD method, then the concentration field and velocity field can be extracted and coupled with the particle movement behavior which can be simulated by DEM. Particle deposition process can be described by the CVD model based on particle position, velocity and neighboring gas concentration. This multiscale coupling method can be implemented in the Fluent@-EDEM@ software with their UDF (User Definition Function) and API (Application Programming Interface). Base on the multiscale coupling concept, the criterion for evaluating FB-CVD process is given. At first, the volume in the coating furnace is divided into two parts (active coating area and non-active coating area) based on simulation results of chemical pyrolysis process. Then the residence time of all particles in the active coating area can be obtained using the CFD-DEM simulation method. The residence time distribution can be used as a criterion for evaluating the gas-solid contact efficiency and operation performance of the coating furnace. At last different coating parameters of the coating furnace are compared based on the proposed criterion. And also, the future research emphasis is discussed. (author)

  20. Drainage network extraction from a high-resolution DEM using parallel programming in the .NET Framework

    Science.gov (United States)

    Du, Chao; Ye, Aizhong; Gan, Yanjun; You, Jinjun; Duan, Qinyun; Ma, Feng; Hou, Jingwen

    2017-12-01

    High-resolution Digital Elevation Models (DEMs) can be used to extract high-accuracy prerequisite drainage networks. A higher resolution represents a larger number of grids. With an increase in the number of grids, the flow direction determination will require substantial computer resources and computing time. Parallel computing is a feasible method with which to resolve this problem. In this paper, we proposed a parallel programming method within the .NET Framework with a C# Compiler in a Windows environment. The basin is divided into sub-basins, and subsequently the different sub-basins operate on multiple threads concurrently to calculate flow directions. The method was applied to calculate the flow direction of the Yellow River basin from 3 arc-second resolution SRTM DEM. Drainage networks were extracted and compared with HydroSHEDS river network to assess their accuracy. The results demonstrate that this method can calculate the flow direction from high-resolution DEMs efficiently and extract high-precision continuous drainage networks.

  1. Preliminary assessment of rockslide and rockfall hazards using a DEM (Oppstadhornet, Norway

    Directory of Open Access Journals (Sweden)

    M.-H. Derron

    2005-01-01

    Full Text Available The increasing availability and precision of digital elevation model (DEM helps in the assessment of landslide prone areas where only few data are available. This approach is performed in 6 main steps which include: DEM creation; identification of geomorphologic features; determination of the main sets of discontinuities; mapping of the most likely dangerous structures; preliminary rock-fall assessment; estimation of the large instabilities volumes. The method is applied to two the cases studies in the Oppstadhornet mountain (730m alt: (1 a 10 millions m3 slow-moving rockslide and (2 a potential high-energy rock falling prone area. The orientations of the foliation and of the major discontinuities have been determined directly from the DEM. These results are in very good agreement with field measurements. Spatial arrangements of discontinuities and foliation with the topography revealed hazardous structures. Maps of potential occurrence of these hazardous structures show highly probable sliding areas at the foot of the main landslide and potential rock falls in the eastern part of the mountain.

  2. Fusion of Laser Altimetry Data with Dems Derived from Stereo Imaging Systems

    Science.gov (United States)

    Schenk, T.; Csatho, B. M.; Duncan, K.

    2016-06-01

    During the last two decades surface elevation data have been gathered over the Greenland Ice Sheet (GrIS) from a variety of different sensors including spaceborne and airborne laser altimetry, such as NASA's Ice Cloud and land Elevation Satellite (ICESat), Airborne Topographic Mapper (ATM) and Laser Vegetation Imaging Sensor (LVIS), as well as from stereo satellite imaging systems, most notably from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Worldview. The spatio-temporal resolution, the accuracy, and the spatial coverage of all these data differ widely. For example, laser altimetry systems are much more accurate than DEMs derived by correlation from imaging systems. On the other hand, DEMs usually have a superior spatial resolution and extended spatial coverage. We present in this paper an overview of the SERAC (Surface Elevation Reconstruction And Change detection) system, designed to cope with the data complexity and the computation of elevation change histories. SERAC simultaneously determines the ice sheet surface shape and the time-series of elevation changes for surface patches whose size depends on the ruggedness of the surface and the point distribution of the sensors involved. By incorporating different sensors, SERAC is a true fusion system that generates the best plausible result (time series of elevation changes) a result that is better than the sum of its individual parts. We follow this up with an example of the Helmheim gacier, involving ICESat, ATM and LVIS laser altimetry data, together with ASTER DEMs.

  3. A Seamless, High-Resolution, Coastal Digital Elevation Model (DEM) for Southern California

    Science.gov (United States)

    Barnard, Patrick L.; Hoover, Daniel

    2010-01-01

    A seamless, 3-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the Mexican border. The goal was to integrate the most recent, high-resolution datasets available (for example, Light Detection and Ranging (Lidar) topography, multibeam and single beam sonar bathymetry, and Interferometric Synthetic Aperture Radar (IfSAR) topography) into a continuous surface from at least the 20-m isobath to the 20-m elevation contour. This dataset was produced to provide critical boundary conditions (bathymetry and topography) for a modeling effort designed to predict the impacts of severe winter storms on the Southern California coast (Barnard and others, 2009). The hazards model, run in real-time or with prescribed scenarios, incorporates atmospheric information (wind and pressure fields) with a suite of state-of-the-art physical process models (tide, surge, and wave) to enable detailed prediction of water levels, run-up, wave heights, and currents. Research-grade predictions of coastal flooding, inundation, erosion, and cliff failure are also included. The DEM was constructed to define the general shape of nearshore, beach and cliff surfaces as accurately as possible, with less emphasis on the detailed variations in elevation inland of the coast and on bathymetry inside harbors. As a result this DEM should not be used for navigation purposes.

  4. Fatores que influenciam a qualidade de vida do cuidador familiar do idoso com demência

    Directory of Open Access Journals (Sweden)

    Lírica Salluz Mattos Pereira

    2015-12-01

    Full Text Available Resumo A piora do quadro clínico na demência leva a perda da autonomia e independência do idoso. Tal contexto pressupõe que algum familiar irá assumir as funções de cuidador, o que pode interferir na sua qualidade de vida (QV. A presente investigação é uma revisão integrativa que teve como objetivo analisar as evidências disponíveis sobre os fatores que influenciam a QV do cuidador familiar do idoso com demência. Foram selecionados artigos publicados nas bases dados BDENF, Lilacs e Medline, tendo sido identificados 477 estudos, dos quais 11 atenderam aos critérios de inclusão e compuseram a amostra desta revisão. Identificou-se que os fatores que influenciam a QV desse cuidador são: depressão; má qualidade do sono; tipo de demência e sintomas neuropsiquiátricos; apoio, suporte social e acesso aos serviços de saúde; lazer; problemas de saúde pré-existentes; intervenções com treinamento para o cuidador e espiritualidade. Sugere-se que o profissional enfermeiro identifique necessidades desse cuidador, para que assim possa traçar estratégias de cuidado.

  5. DEM investigation of weathered rocks using a novel bond contact model

    Directory of Open Access Journals (Sweden)

    Zhenming Shi

    2015-06-01

    Full Text Available The distinct element method (DEM incorporated with a novel bond contact model was applied in this paper to shed light on the microscopic physical origin of macroscopic behaviors of weathered rock, and to achieve the changing laws of microscopic parameters from observed decaying properties of rocks during weathering. The changing laws of macroscopic mechanical properties of typical rocks were summarized based on the existing research achievements. Parametric simulations were then conducted to analyze the relationships between macroscopic and microscopic parameters, and to derive the changing laws of microscopic parameters for the DEM model. Equipped with the microscopic weathering laws, a series of DEM simulations of basic laboratory tests on weathered rock samples was performed in comparison with analytical solutions. The results reveal that the relationships between macroscopic and microscopic parameters of rocks against the weathering period can be successfully attained by parametric simulations. In addition, weathering has a significant impact on both stress–strain relationship and failure pattern of rocks.

  6. FUSION OF LASER ALTIMETRY DATA WITH DEMS DERIVED FROM STEREO IMAGING SYSTEMS

    Directory of Open Access Journals (Sweden)

    T. Schenk

    2016-06-01

    Full Text Available During the last two decades surface elevation data have been gathered over the Greenland Ice Sheet (GrIS from a variety of different sensors including spaceborne and airborne laser altimetry, such as NASA’s Ice Cloud and land Elevation Satellite (ICESat, Airborne Topographic Mapper (ATM and Laser Vegetation Imaging Sensor (LVIS, as well as from stereo satellite imaging systems, most notably from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER and Worldview. The spatio-temporal resolution, the accuracy, and the spatial coverage of all these data differ widely. For example, laser altimetry systems are much more accurate than DEMs derived by correlation from imaging systems. On the other hand, DEMs usually have a superior spatial resolution and extended spatial coverage. We present in this paper an overview of the SERAC (Surface Elevation Reconstruction And Change detection system, designed to cope with the data complexity and the computation of elevation change histories. SERAC simultaneously determines the ice sheet surface shape and the time-series of elevation changes for surface patches whose size depends on the ruggedness of the surface and the point distribution of the sensors involved. By incorporating different sensors, SERAC is a true fusion system that generates the best plausible result (time series of elevation changes a result that is better than the sum of its individual parts. We follow this up with an example of the Helmheim gacier, involving ICESat, ATM and LVIS laser altimetry data, together with ASTER DEMs.

  7. Tropical forest heterogeneity from TanDEM-X InSAR and lidar observations in Indonesia

    Science.gov (United States)

    De Grandi, Elsa Carla; Mitchard, Edward

    2016-10-01

    Fires exacerbated during El Niño Southern Oscillation are a serious threat in Indonesia leading to the destruction and degradation of tropical forests and emissions of CO2 in the atmosphere. Forest structural changes which occurred due to the 1997-1998 El Niño Southern Oscillation in the Sungai Wain Protection Forest (East Kalimantan, Indonesia), a previously intact forest reserve have led to the development of a range of landcover from secondary forest to areas dominated by grassland. These structural differences can be appreciated over large areas by remote sensing instruments such as TanDEM-X and LiDAR that provide information that are sensitive to vegetation vertical and horizontal structure. One-point statistics of TanDEM-X coherence (mean and CV) and LiDAR CHM (mean, CV) and derived metrics such as vegetation volume and canopy cover were tested for the discrimination between 4 landcover classes. Jeffries-Matusita (JM) separability was high between forest classes (primary or secondary forest) and non-forest (grassland) while, primary and secondary forest were not separable. The study tests the potential and the importance of potential of TanDEM-X coherence and LiDAR observations to characterize structural heterogeneity based on one-point statistics in tropical forest but requires improved characterization using two-point statistical measures.

  8. 2000 Jahre Varusschlacht: Bücher aus dem Bestand der Universitäts- und Landesbibliothek Münster

    OpenAIRE

    Mühl, H. (Hans)

    2014-01-01

    Verzeichnis selbständiger Schriften zur Varusschlacht, ihrer Erforschung und Rezeption aus dem Bestand der Universitäts- und Landesbibliothek Münster (mit Signaturangaben) zum Jubiläum der Varusschlacht 2009.

  9. VT Lidar Hydro-flattened DEM (0.7 meter) - 2013 - Rutland/West Washington/Grand Isle

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area: Rutland/GI Counties 2013 0.7m and Digital Elevation Model (DEM) datasets of various...

  10. VT Data - Lidar Hydro-flattened DEM (0.7m) 2016, Essex, Caledonia, Orange, and Windsor Counties

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Middle CT River subbasin 2016 0.7m and Digital Elevation Model (DEM) dataset of the...

  11. Joint use of multi-orbit high-resolution SAR interferometry for DEM generation in mountainous area

    KAUST Repository

    Zhang, Lu

    2014-07-01

    SAR interferometry has long been regarded as an effective tool for wide-area topographic mapping in hilly and mountainous areas. However, quality of InSAR DEM product is usually affected by atmospheric disturbances and decorrelation-induced voids, especially for data acquired in repeat-pass mode. In this paper, we proposed an approach for improved topographic mapping by optimal fusion of multi-orbit InSAR DEMs with correction of atmospheric phase screen (APS). An experimental study with highresolution TerraSAR-X and COSMO-SkyMed datasets covering a mountainous area was carried out to demonstrate the effectiveness of the proposed approach. Validation with a reference DEM of scale 1:50,000 indicated that vertical accuracy of the fused DEM can be better than 5 m.

  12. Defining optimal DEM resolutions and point densities for modelling hydrologically sensitive areas in agricultural catchments dominated by microtopography

    Science.gov (United States)

    Thomas, I. A.; Jordan, P.; Shine, O.; Fenton, O.; Mellander, P.-E.; Dunlop, P.; Murphy, P. N. C.

    2017-02-01

    Defining critical source areas (CSAs) of diffuse pollution in agricultural catchments depends upon the accurate delineation of hydrologically sensitive areas (HSAs) at highest risk of generating surface runoff pathways. In topographically complex landscapes, this delineation is constrained by digital elevation model (DEM) resolution and the influence of microtopographic features. To address this, optimal DEM resolutions and point densities for spatially modelling HSAs were investigated, for onward use in delineating CSAs. The surface runoff framework was modelled using the Topographic Wetness Index (TWI) and maps were derived from 0.25 m LiDAR DEMs (40 bare-earth points m-2), resampled 1 m and 2 m LiDAR DEMs, and a radar generated 5 m DEM. Furthermore, the resampled 1 m and 2 m LiDAR DEMs were regenerated with reduced bare-earth point densities (5, 2, 1, 0.5, 0.25 and 0.125 points m-2) to analyse effects on elevation accuracy and important microtopographic features. Results were compared to surface runoff field observations in two 10 km2 agricultural catchments for evaluation. Analysis showed that the accuracy of modelled HSAs using different thresholds (5%, 10% and 15% of the catchment area with the highest TWI values) was much higher using LiDAR data compared to the 5 m DEM (70-100% and 10-84%, respectively). This was attributed to the DEM capturing microtopographic features such as hedgerow banks, roads, tramlines and open agricultural drains, which acted as topographic barriers or channels that diverted runoff away from the hillslope scale flow direction. Furthermore, the identification of 'breakthrough' and 'delivery' points along runoff pathways where runoff and mobilised pollutants could be potentially transported between fields or delivered to the drainage channel network was much higher using LiDAR data compared to the 5 m DEM (75-100% and 0-100%, respectively). Optimal DEM resolutions of 1-2 m were identified for modelling HSAs, which balanced the need

  13. Extraction and Validation of Geomorphological Features from EU-DEM in The Vicinity of the Mygdonia Basin, Northern Greece

    Science.gov (United States)

    Mouratidis, Antonios; Karadimou, Georgia; Ampatzidis, Dimitrios

    2017-12-01

    The European Union Digital Elevation Model (EU-DEM) is a relatively new, hybrid elevation product, principally based on SRTM DEM and ASTER GDEM data, but also on publically available Russian topographic maps for regions north of 60° N. More specifically, EU-DEM is a Digital Surface Model (DSM) over Europe from the Global Monitoring for Environment and Security (GMES) Reference Data Access (RDA) project - a realisation of the Copernicus (former GMES) programme, managed by the European Commission/DG Enterprise and Industry. Even if EU-DEM is indeed more reliable in terms of elevation accuracy than its constituents, it ought to be noted that it is not representative of the original elevation measurements, but is rather a secondary (mathematical) product. Therefore, for specific applications, such as those of geomorphological interest, artefacts may be induced. To this end, the purpose of this paper is to investigate the performance of EU-DEM for geomorphological applications and compare it against other available datasets, i.e. topographic maps and (almost) global DEMs such as SRTM, ASTER-GDEM and WorldDEM™. This initial investigation is carried out in Central Macedonia, Northern Greece, in the vicinity of the Mygdonia basin, which corresponds to an area of particular interest for several geoscience applications. This area has also been serving as a test site for the systematic validation of DEMs for more than a decade. Consequently, extensive elevation datasets and experience have been accumulated over the years, rendering the evaluation of new elevation products a coherent and useful exercise on a local to regional scale. In this context, relief classification, drainage basin delineation, slope and slope aspect, as well as extraction and classification of drainage network are performed and validated among the aforementioned elevation sources. The achieved results focus on qualitative and quantitative aspects of automatic geomorphological feature extraction from

  14. Modifying Young's modulus in DEM simulations based on distributions of experimental measurements

    Energy Technology Data Exchange (ETDEWEB)

    Van Lew, Jon T., E-mail: jtvanlew@fusion.ucla.edu [UCLA, MAE Department, 44-114 Engineering IV, 420 Westwood Plaza, Los Angeles, CA 90095-1597 (United States); Park, Yi-Hyun [National Fusion Research Institute, Daejeon (Korea, Republic of); Ying, Alice; Abdou, Mohamed [UCLA, MAE Department, 44-114 Engineering IV, 420 Westwood Plaza, Los Angeles, CA 90095-1597 (United States)

    2015-10-15

    Highlights: • Developing a modification to the Young's modulus of individual pebbles based on variations seen in single pebble crushing experiments. • Developing an equation to translate between single pebble crush data to a “force value” that can be applied to individual pebbles in DEM simulations. • Applying the above developments into DEM simulations on uniaxial compression tests, with parametric variations on pebble diameter distribution and pebble coefficient of friction. • Found that modified Young's modulus simulations resulted in pebbles that predicted fewer broken pebbles than the older, single value Young's modulus version of DEM models. - Abstract: The discrete element method, as currently employed by members of the fusion community, is rooted on the assumption that each pebble is a perfectly elastic material that obeys Hertz's theory for normal interaction. This assumption impacts the magnitude of inter-particle forces predicted by the models. We scrutinize the Hertzian assumption with single-pebble crush experiments with carefully recorded force-displacement responses and compare them to the non-linear forces predicted by a Hertzian pebble with bulk properties reported in literature. We found each pebble generally has a non-linear force response but with varying levels of stiffness that qualitatively matched the curves from Hertz theory. Assuming Hertzian interaction, we backed-out an elastic modulus for each pebble. We define a softening coefficient, κ, as the ratio of the pebble's elastic modulus to the sintered bulk value from literature. After determining the κ value for every pebble in our batch, we discovered a probability distribution for different batches. The distribution is attributed to the varying micro-structure of each pebble. We incorporate the results into our DEM algorithms, distributing κ values at random to pebbles satisfying the probability curves of experiments. DEM simulations of pebble beds

  15. DEM EXTRACTION FROM WORLDVIEW-3 STEREO-IMAGES AND ACCURACY EVALUATION

    Directory of Open Access Journals (Sweden)

    F. Hu

    2016-06-01

    Full Text Available This paper validates the potentials of Worldview-3 satellite images in large scale topographic mapping, by choosing Worldview-3 along-track stereo-images of Yi Mountain area in Shandong province China for DEM extraction and accuracy evaluation. Firstly, eighteen accurate and evenly-distributed GPS points are collected in field and used as GCPs/check points, the image points of which are accurately measured, and also tie points are extracted from image matching; then, the RFM-based block adjustment to compensate the systematic error in image orientation is carried out and the geo-positioning accuracy is calculated and analysed; next, for the two stereo-pairs of the block, DSMs are separately constructed and mosaicked as an entirety, and also the corresponding DEM is subsequently generated; finally, compared with the selected check points from high-precision airborne LiDAR point cloud covering the same test area, the accuracy of the generated DEM with 2-meter grid spacing is evaluated by the maximum (max., minimum (min., mean and standard deviation (std. values of elevation biases. It is demonstrated that, for Worldview-3 stereo-images used in our research, the planimetric accuracy without GCPs is about 2.16 m (mean error and 0.55 (std. error, which is superior to the nominal value, while the vertical accuracy is about -1.61 m (mean error and 0.49 m (std. error; with a small amount of GCPs located in the center and four corners of the test area, the systematic error can be well compensated. The std. value of elevation biases between the generated DEM and the 7256 LiDAR check points are about 0.62 m. If considering the potential uncertainties in the image point measurement, stereo matching and also elevation editing, the accuracy of generating DEM from Worldview-3 stereo-images should be more desirable. Judging from the results, Worldview-3 has the potential for 1:5000 or even larger scale mapping application.

  16. A Hybrid Process/Thread Parallel Algorithm for Generating DEM from LiDAR Points

    Directory of Open Access Journals (Sweden)

    Yibin Ren

    2017-09-01

    Full Text Available Airborne Light Detection and Ranging (LiDAR is widely used in digital elevation model (DEM generation. However, the very large volume of LiDAR datasets brings a great challenge for the traditional serial algorithm. Using parallel computing to accelerate the efficiency of DEM generation from LiDAR points has been a hot topic in parallel geo-computing. Generally, most of the existing parallel algorithms running on high-performance clusters (HPC were in process-paralleling mode, with a static scheduling strategy. The static strategy would not respond dynamically according to the computation progress, leading to load unbalancing. Additionally, because each process has independent memory space, the cost of dealing with boundary problems increases obviously with the increase in the number of processes. Actually, these two problems can have a significant influence on the efficiency of DEM generation for larger datasets, especially for those of irregular shapes. Thus, to solve these problems, we combined the advantages of process-paralleling with the advantages of thread-paralleling, forming a new idea: using process-paralleling to achieve a flexible schedule and scalable computation, using thread-paralleling inside the process to reduce boundary problems. Therefore, we proposed a hybrid process/thread parallel algorithm for generating DEM from LiDAR points. Firstly, at the process level, we designed a parallel method (PPDB to accelerate the partitioning of LiDAR points. We also proposed a new dynamic scheduling strategy to achieve better load balancing. Secondly, at the thread level, we designed an asynchronous parallel strategy to hide the cost of LiDAR points’ reading. Lastly, we tested our algorithm with three LiDAR datasets. Experiments showed that our parallel algorithm had no influence on the accuracy of the resultant DEM. At the same time, our algorithm reduced the conversion time from 112,486 s to 2342 s when we used the largest dataset (150

  17. Kultuuriruum ja Natalie Mei prostitutsiooniteemalised joonistused / Kai Stahl

    Index Scriptorium Estoniae

    Stahl, Kai

    2011-01-01

    Analüüsitakse feministliku lugemise ja Juri Lotmani kultuurisemiootika abil kultuuri ja "mittekultuuri" vahelist piiriala, keskendudes viisidele, kuidas Natalie Mei erines oma joonistustega kunsti üldpildist - rikkudes traditsionaalset pildikoodi, ironiseerib Mei selle teema domineerivat käsitlust ja pildilist kuvamist, luues naiskunstnikuna uue vaatenurga

  18. Creating High Quality DEMs of Large Scale Fluvial Environments Using Structure-from-Motion

    Science.gov (United States)

    Javernick, L. A.; Brasington, J.; Caruso, B. S.; Hicks, M.; Davies, T. R.

    2012-12-01

    During the past decade, advances in survey and sensor technology have generated new opportunities to investigate the structure and dynamics of fluvial systems. Key geomatic technologies include the Global Positioning System (GPS), digital photogrammetry, LiDAR, and terrestrial laser scanning (TLS). The application of such has resulted in a profound increase in the dimensionality of topographic surveys - from cross-sections to distributed 3d point clouds and digital elevation models (DEMs). Each of these technologies have been used successfully to derive high quality DEMs of fluvial environments; however, they often require specialized and expensive equipment, such as a TLS or large format camera, bespoke platforms such as survey aircraft, and consequently make data acquisition prohibitively expensive or highly labour intensive, thus restricting the extent and frequency of surveys. Recently, advances in computer vision and image analysis have led to development of a novel photogrammetric approach that is fully automated and suitable for use with simple compact (non-metric) cameras. In this paper, we evaluate a new photogrammetric method, Structure-from-Motion (SfM), and demonstrate how this can be used to generate DEMs of comparable quality to airborne LiDAR, using consumer grade cameras at low costs. Using the SfM software PhotoScan (version 0.8.5), high quality DEMs were produced for a 1.6 km reach and a 3.3 km reach of the braided Ahuriri River, New Zealand. Photographs used for DEM creation were acquired from a helicopter flying at 600 m and 800 m above ground level using a consumer grade 10.1mega-pixel, non-metric digital camera, resulting in object space resolution imagery of 0.12 m and 0.16 m respectively. Point clouds for the two study reaches were generated using 147 and 224 photographs respectively, and were extracted automatically in an arbitrary coordinate system; RTK-GPS located ground control points (GCPs) were used to define a 3d non

  19. Coupling photogrammetric data with DFN-DEM model for rock slope hazard assessment

    Science.gov (United States)

    Donze, Frederic; Scholtes, Luc; Bonilla-Sierra, Viviana; Elmouttie, Marc

    2013-04-01

    Structural and mechanical analyses of rock mass are key components for rock slope stability assessment. The complementary use of photogrammetric techniques [Poropat, 2001] and coupled DFN-DEM models [Harthong et al., 2012] provides a methodology that can be applied to complex 3D configurations. DFN-DEM formulation [Scholtès & Donzé, 2012a,b] has been chosen for modeling since it can explicitly take into account the fracture sets. Analyses conducted in 3D can produce very complex and unintuitive failure mechanisms. Therefore, a modeling strategy must be established in order to identify the key features which control the stability. For this purpose, a realistic case is presented to show the overall methodology from the photogrammetry acquisition to the mechanical modeling. By combining Sirovision and YADE Open DEM [Kozicki & Donzé, 2008, 2009], it can be shown that even for large camera to rock slope ranges (tested about one kilometer), the accuracy of the data are sufficient to assess the role of the structures on the stability of a jointed rock slope. In this case, on site stereo pairs of 2D images were taken to create 3D surface models. Then, digital identification of structural features on the unstable block zone was processed with Sirojoint software [Sirovision, 2010]. After acquiring the numerical topography, the 3D digitalized and meshed surface was imported into the YADE Open DEM platform to define the studied rock mass as a closed (manifold) volume to define the bounding volume for numerical modeling. The discontinuities were then imported as meshed planar elliptic surfaces into the model. The model was then submitted to gravity loading. During this step, high values of cohesion were assigned to the discontinuities in order to avoid failure or block displacements triggered by inertial effects. To assess the respective role of the pre-existing discontinuities in the block stability, different configurations have been tested as well as different degree of

  20. Coastal Digital Elevation Models (DEMs) for tsunami hazard assessment on the French coasts

    Science.gov (United States)

    Maspataud, Aurélie; Biscara, Laurie; Hébert, Hélène; Schmitt, Thierry; Créach, Ronan

    2015-04-01

    Building precise and up-to-date coastal DEMs is a prerequisite for accurate modeling and forecasting of hydrodynamic processes at local scale. Marine flooding, originating from tsunamis, storm surges or waves, is one of them. Some high resolution DEMs are being generated for multiple coast configurations (gulf, embayment, strait, estuary, harbor approaches, low-lying areas…) along French Atlantic and Channel coasts. This work is undertaken within the framework of the TANDEM project (Tsunamis in the Atlantic and the English ChaNnel: Definition of the Effects through numerical Modeling) (2014-2017). DEMs boundaries were defined considering the vicinity of French civil nuclear facilities, site effects considerations and potential tsunamigenic sources. Those were identified from available historical observations. Seamless integrated topographic and bathymetric coastal DEMs will be used by institutions taking part in the study to simulate expected wave height at regional and local scale on the French coasts, for a set of defined scenarii. The main tasks were (1) the development of a new capacity of production of DEM, (2) aiming at the release of high resolution and precision digital field models referred to vertical reference frameworks, that require (3) horizontal and vertical datum conversions (all source elevation data need to be transformed to a common datum), on the basis of (4) the building of (national and/or local) conversion grids of datum relationships based on known measurements. Challenges in coastal DEMs development deal with good practices throughout model development that can help minimizing uncertainties. This is particularly true as scattered elevation data with variable density, from multiple sources (national hydrographic services, state and local government agencies, research organizations and private engineering companies) and from many different types (paper fieldsheets to be digitized, single beam echo sounder, multibeam sonar, airborne laser

  1. Landform classification using a sub-pixel spatial attraction model to increase spatial resolution of digital elevation model (DEM

    Directory of Open Access Journals (Sweden)

    Marzieh Mokarrama

    2018-04-01

    Full Text Available The purpose of the present study is preparing a landform classification by using digital elevation model (DEM which has a high spatial resolution. To reach the mentioned aim, a sub-pixel spatial attraction model was used as a novel method for preparing DEM with a high spatial resolution in the north of Darab, Fars province, Iran. The sub-pixel attraction models convert the pixel into sub-pixels based on the neighboring pixels fraction values, which can only be attracted by a central pixel. Based on this approach, a mere maximum of eight neighboring pixels can be selected for calculating of the attraction value. In the mentioned model, other pixels are supposed to be far from the central pixel to receive any attraction. In the present study by using a sub-pixel attraction model, the spatial resolution of a DEM was increased. The design of the algorithm is accomplished by using a DEM with a spatial resolution of 30 m (the Advanced Space borne Thermal Emission and Reflection Radiometer; (ASTER and a 90 m (the Shuttle Radar Topography Mission; (SRTM. In the attraction model, scale factors of (S = 2, S = 3, and S = 4 with two neighboring methods of touching (T = 1 and quadrant (T = 2 are applied to the DEMs by using MATLAB software. The algorithm is evaluated by taking the best advantages of 487 sample points, which are measured by surveyors. The spatial attraction model with scale factor of (S = 2 gives better results compared to those scale factors which are greater than 2. Besides, the touching neighborhood method is turned to be more accurate than the quadrant method. In fact, dividing each pixel into more than two sub-pixels decreases the accuracy of the resulted DEM. On the other hand, in these cases DEM, is itself in charge of increasing the value of root-mean-square error (RMSE and shows that attraction models could not be used for S which is greater than 2. Thus considering results, the proposed model is highly capable of

  2. A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment

    Directory of Open Access Journals (Sweden)

    A. J. Cook

    2012-10-01

    Full Text Available A high resolution surface topography Digital Elevation Model (DEM is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63–70° S, based on ASTER Global Digital Elevation Model (GDEM data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA imagery. The new DEM has a mean elevation difference of −4 m (± 25 m RMSE from ICESat (compared to −13 m mean and ±97 m RMSE for the original ASTER GDEM, and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: http://nsidc.org/data/nsidc-0516.html (Simulation of a tablet coating process at different scales using DEM.

    Science.gov (United States)

    Boehling, P; Toschkoff, G; Just, S; Knop, K; Kleinebudde, P; Funke, A; Rehbaum, H; Rajniak, P; Khinast, J G

    2016-10-10

    Spray coating of tablets is an important unit operation in the pharmaceutical industry and is mainly used for modified release, enteric protection, better appearance and brand recognition. It can also be used to apply an additional active pharmaceutical ingredient to the tablet core. Scale-up of such a process is an important step in commercialization. However, scale-up is not trivial and frequently, at manufacturing scales the required coating quality cannot be reached. Thus, we propose a method where laboratory experiments are carried out, yet scale-up is done via computational methods, i.e., by extrapolating results to larger scales. In the recent years, the Discrete Element Method (DEM) has widely been used to simulate tablet behavior in a laboratory scale drum coater. Due the increasing computational power and more sophisticated DEM algorithms, it has become possible to simulate millions of particles on regular PCs and model industrial scale tablet coating devices. In this work, simulations were performed on the laboratory, pilot and industrial scales and DEM was used to study how different scale-up rules influence the bed behavior on larger scales. The material parameters of the tablets were measured in the laboratory and a glued sphere approach was applied to model the tablet shape. The results include a vast amount of qualitative and quantitative data at the different scales. In conclusion, the evolution of the inter-tablet coating variation for the different scales and process parameters is presented. The results suggest that keeping the Froude number constant during the scale up process leads to faster processes as the cycle time is shorter and the spray residence time is more uniform when compared to keeping the circumferential velocity constant. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. DEVELOPMENT AND EVALUATION OF SIMPLE MEASUREMENT SYSTEM USING THE OBLIQUE PHOTO AND DEM

    Directory of Open Access Journals (Sweden)

    H. Nonaka

    2016-06-01

    Full Text Available When a disaster occurs, we must grasp and evaluate its damage as soon as possible. Then we try to estimate them from some kind of photographs, such as surveillance camera imagery, satellite imagery, photographs taken from a helicopter and so on. Especially in initial stage, estimation of decent damage situation for a short time is more important than investigation of damage situation for a long time. One of the source of damage situation is the image taken by surveillance camera, satellite sensor and helicopter. If we can measure any targets in these imagery, we can estimate a length of a lava flow, a reach of a cinder and a sediment volume in volcanic eruption or landslide. Therefore in order to measure various information for a short time, we developed a simplified measurement system which uses these photographs. This system requires DEM in addition to photographs, but it is possible to use previously acquired DEM. To measure an object, we require only two steps. One is the determination of the position and the posture in which the photograph is shot. We determine these parameters using DEM. The other step is the measurement of an object in photograph. In this paper, we describe this system and show the experimental results to evaluate this system. In this experiment we measured the top of Mt. Usu by using two measurement method of this system. Then we can measure it about one hour and the difference between the measurement results and the airborne LiDAR data are less than 10 meter.

  4. ANALYSIS AND VALIDATION OF GRID DEM GENERATION BASED ON GAUSSIAN MARKOV RANDOM FIELD

    Directory of Open Access Journals (Sweden)

    F. J. Aguilar

    2016-06-01

    Full Text Available Digital Elevation Models (DEMs are considered as one of the most relevant geospatial data to carry out land-cover and land-use classification. This work deals with the application of a mathematical framework based on a Gaussian Markov Random Field (GMRF to interpolate grid DEMs from scattered elevation data. The performance of the GMRF interpolation model was tested on a set of LiDAR data (0.87 points/m2 provided by the Spanish Government (PNOA Programme over a complex working area mainly covered by greenhouses in Almería, Spain. The original LiDAR data was decimated by randomly removing different fractions of the original points (from 10% to up to 99% of points removed. In every case, the remaining points (scattered observed points were used to obtain a 1 m grid spacing GMRF-interpolated Digital Surface Model (DSM whose accuracy was assessed by means of the set of previously extracted checkpoints. The GMRF accuracy results were compared with those provided by the widely known Triangulation with Linear Interpolation (TLI. Finally, the GMRF method was applied to a real-world case consisting of filling the LiDAR-derived DSM gaps after manually filtering out non-ground points to obtain a Digital Terrain Model (DTM. Regarding accuracy, both GMRF and TLI produced visually pleasing and similar results in terms of vertical accuracy. As an added bonus, the GMRF mathematical framework makes possible to both retrieve the estimated uncertainty for every interpolated elevation point (the DEM uncertainty and include break lines or terrain discontinuities between adjacent cells to produce higher quality DTMs.

  5. A 3D DEM-LBM approach for the assessment of the quick condition for sands

    Science.gov (United States)

    Mansouri, M.; Delenne, J.-Y.; El Youssoufi, M. S.; Seridi, A.

    2009-09-01

    We present a 3D numerical model to assess the quick condition (the onset of the boiling phenomenon) in a saturated polydisperse granular material. We use the Discrete Element Method (DEM) to study the evolution of the vertical intergranular stress in a granular sample subjected to an increasing hydraulic gradient. The hydrodynamic forces on the grains of the sample are computed using the Lattice Boltzmann Method (LBM). The principal assumption used is that grains remain at rest until the boiling onset. We show that the obtained critical hydraulic gradient is close to that defined in classical soil mechanics. To cite this article: M. Mansouri et al., C. R. Mecanique 337 (2009).

  6. Deep Convolutional Generative Adversarial Network for Procedural 3D Landscape Generation Based on DEM

    DEFF Research Database (Denmark)

    Wulff-Jensen, Andreas; Rant, Niclas Nerup; Møller, Tobias Nordvig

    2017-01-01

    This paper proposes a novel framework for improving procedural generation of 3D landscapes using machine learning. We utilized a Deep Convolutional Generative Adversarial Network (DC-GAN) to generate heightmaps. The network was trained on a dataset consisting of Digital Elevation Maps (DEM......) of the alps. During map generation, the batch size and learning rate were optimized for the most efficient and satisfying map production. The diversity of the final output was tested against Perlin noise using Mean Square Error [1] and Structure Similarity Index [2]. Perlin noise is especially interesting...

  7. DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

    International Nuclear Information System (INIS)

    Seward, F. D.; Charles, P. A.; Foster, D. L.; Dickel, J. R.; Romero, P. S.; Edwards, Z. I.; Perry, M.; Williams, R. M.

    2012-01-01

    A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M ☉

  8. DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

    Energy Technology Data Exchange (ETDEWEB)

    Seward, F. D. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Charles, P. A. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Foster, D. L. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Dickel, J. R.; Romero, P. S. [Department of Physics and Astronomy, University of New Mexico, 1919 Lomas Boulevard NE, Albuquerque, NM 87131 (United States); Edwards, Z. I.; Perry, M.; Williams, R. M. [Department of Earth and Space Sciences, Columbus State University, Coca Cola Space Science Center, 701 Front Avenue, Columbus, GA 31901 (United States)

    2012-11-10

    A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M {sub Sun}.

  9. Untersuchung der Produktion charmhaltiger Mesonen in der Photon-Photon-Streuung mit dem OPAL-Experiment

    OpenAIRE

    Patt, Jochen

    2001-01-01

    Die Produktion von Charm-Quarks in der Photon-Photon-Streuung wird ueber den Nachweis charmhaltiger Mesonen untersucht. Die Arbeit basiert auf den Daten, die mit dem OPAL-Detektor am Elektron-Positron-Speicherring LEP am CERN in Genf in den Jahren von 1989 bis 1998 aufgenommen worden sind. Anhand des Charmonium-Zustandes Chi(c2) wird die Resonanzproduktion von Charm-Quarks untersucht und die Zwei-Photon-Breite des Chi(c2)-Mesons wird gemessen. Geladene D*-Mesonen werden zur Untersuchung der o...

  10. Combined DFT and DEMS investigation of the effect of dopants in secondary zinc‐air batteries

    DEFF Research Database (Denmark)

    Lysgaard, Steen; Christensen, Mathias K.; Hansen, Heine A.

    2018-01-01

    Zinc‐air batteries offer the potential of low cost energy storage with high energy density, but at present secondary batteries suffer from poor cyclability. To develop secondary Zn‐air batteries, several challenges need to be overcome: choking of the cathode, catalyzing the oxygen evolution...... and reduction reactions, limiting dendrite formation and the hydrogen evolution reaction (HER). Understanding and alleviating HER at the anode is a challenge, where it is necessary to involve computational as well as experimental research. Here, we combine Differential Electrochemical Mass Spectrometry (DEMS...

  11. Demência como fator de risco para fraturas graves em idosos

    Directory of Open Access Journals (Sweden)

    Carvalho Aline de Mesquita

    2002-01-01

    Full Text Available INTRODUÇÃO: As quedas entre pessoas idosas constituem importante problema de saúde pública devido à sua alta incidência, às complicações para a saúde e aos altos custos assistenciais. O estudo realizado visa a estimar a associação entre demência e ocorrência de quedas e fraturas entre idosos. MÉTODOS: Foi conduzido estudo caso-controle de 404 indivíduos com 60 ou mais anos de idade, da cidade do Rio de Janeiro, Brasil. Casos e controles foram pareados por idade, sexo e hospital. Os dados foram coletados por meio de entrevista estruturada com os idosos. Foram considerados portadores de quadro demencial idosos cuja pontuação no questionário BOAS fosse superior a dois. Foram obtidos odds ratios (OR ajustados por fatores potenciais de confusão, utilizando-se regressão logística condicional. RESULTADOS: As quedas distribuíram-se igualmente entre os períodos da manhã, tarde e noite, havendo uma redução em sua freqüência durante a madrugada. Acidentaram-se dentro de casa 78% dos idosos com demência, contra 55% daqueles sem essa doença. O OR não-ajustado para a associação entre demência e fratura grave foi de 2,0 (IC95%, 1,23-3,25. Após o ajuste por fatores de confusão, houve uma pequena redução dessa associação (OR=1,82, 1,03-3,23. CONCLUSÃO: Idosos com quadro demencial apresentam maior risco de caírem e ser hospitalizados por fratura do que idosos sem demência. Tal fato implica a necessidade de cuidados especiais com esses indivíduos, visando a minimizar o risco desses acidentes.

  12. Grenz-Rede. Annette von Droste-Hülshoffs "Klänge aus dem Orient"

    OpenAIRE

    Wagner-Egelhaaf, Martina

    2010-01-01

    Am 19. 7. 1838 schrieb Annette von Droste-Hülshoff an Christoph Bernhard Schlüter (1801-1884), der zusammen mit seinem Schwager Wilhelm Junkmann (1811-1886) die Betreuung ihrer ersten Gedichtausgabe übernommen hatte: "ich habe, vor einiger Zeit, eine Anzahl morgenländischer Gedichte, zur Auswahl an Jungmann geschickt, weder in Ihrem Briefe noch in dem Seinigen wird Deren erwähnt, sie werden doch nicht verloren gegangen seyn?" Annette von Droste-Hülshoff erhielt erst eine Antwort, nachdem die ...

  13. Demência como fator de risco para fraturas graves em idosos

    Directory of Open Access Journals (Sweden)

    Aline de Mesquita Carvalho

    2002-08-01

    Full Text Available INTRODUÇÃO: As quedas entre pessoas idosas constituem importante problema de saúde pública devido à sua alta incidência, às complicações para a saúde e aos altos custos assistenciais. O estudo realizado visa a estimar a associação entre demência e ocorrência de quedas e fraturas entre idosos. MÉTODOS: Foi conduzido estudo caso-controle de 404 indivíduos com 60 ou mais anos de idade, da cidade do Rio de Janeiro, Brasil. Casos e controles foram pareados por idade, sexo e hospital. Os dados foram coletados por meio de entrevista estruturada com os idosos. Foram considerados portadores de quadro demencial idosos cuja pontuação no questionário BOAS fosse superior a dois. Foram obtidos odds ratios (OR ajustados por fatores potenciais de confusão, utilizando-se regressão logística condicional. RESULTADOS: As quedas distribuíram-se igualmente entre os períodos da manhã, tarde e noite, havendo uma redução em sua freqüência durante a madrugada. Acidentaram-se dentro de casa 78% dos idosos com demência, contra 55% daqueles sem essa doença. O OR não-ajustado para a associação entre demência e fratura grave foi de 2,0 (IC95%, 1,23-3,25. Após o ajuste por fatores de confusão, houve uma pequena redução dessa associação (OR=1,82, 1,03-3,23. CONCLUSÃO: Idosos com quadro demencial apresentam maior risco de caírem e ser hospitalizados por fratura do que idosos sem demência. Tal fato implica a necessidade de cuidados especiais com esses indivíduos, visando a minimizar o risco desses acidentes.

  14. Der Zusammenhang von Partnermarktopportunitäten aus dem Freundeskreis und der Stabilität von Paarbeziehungen : Eine Analyse mit den Daten des Partnermarktsurvey

    OpenAIRE

    Häring, Armando

    2014-01-01

    "Der Beitrag analysiert den Zusammenhang zwischen Partnermarktoportunitäten aus dem Freundeskreis und der Stabilität von Paarbeziehungen. Unter Verwendung des theoretischen Konzepts der Theorie der Interaktionsgelegenheiten sowie von Annahmen der Austauschtheorie und der Familienökonomie, werden mögliche Zusammenhänge zwischen gemeinsamen Freundeskreisen mit dem Partner, Partnermarktgelegenheiten aus dem Freundeskreis (sex ratio) und der Stabilität von Paarbeziehungen diskutiert. Der Beitrag ...

  15. Finding the service you need: human centered design of a Digital Interactive Social Chart in DEMentia care (DEM-DISC).

    Science.gov (United States)

    van der Roest, H G; Meiland, F J M; Haaker, T; Reitsma, E; Wils, H; Jonker, C; Dröes, R M

    2008-01-01

    Community dwelling people with dementia and their informal carers experience a lot of problems. In the course of the disease process people with dementia become more dependent on others and professional help is often necessary. Many informal carers and people with dementia experience unmet needs with regard to information on the disease and on the available care and welfare offer, therefore they tend not to utilize the broad spectrum of available care and welfare services. This can have very negative consequences like unsafe situations, social isolation of the person with dementia and overburden of informal carers with consequent increased risk of illness for them. The development of a DEMentia specific Digital Interactive Social Chart (DEM-DISC) may counteract these problems. DEM-DISC is a demand oriented website for people with dementia and their carers, which is easy, accessible and provides users with customized information on healthcare and welfare services. DEM-DISC is developed according to the human centered design principles, this means that people with dementia, informal carers and healthcare professionals were involved throughout the development process. This paper describes the development of DEM-DISC from four perspectives, a domain specific content perspective, an ICT perspective, a user perspective and an organizational perspective. The aims and most important results from each perspective will be discussed. It is concluded that the human centered design was a valuable method for the development of the DEM-DISC.

  16. Validation of DEM modeling of sintering using an in situ X-ray microtomography analysis of the sintering of NaCl powder

    Science.gov (United States)

    Martin, Sylvain; Navarro, Sebastián; Palancher, Hervé; Bonnin, Anne; Léchelle, Jacques; Guessasma, Mohamed; Fortin, Jérôme; Saleh, Khashayar

    2016-11-01

    This paper aims to validate the discrete element method (DEM) model of sintering. In situ X-ray microtomography experiments have been carried out at the ESRF to follow the sintering of NaCl powder, the properties of which are close to the DEM model assumptions. DEM simulations are then run using an improved implicit method. The comparison between experiment and simulation shows the capability of DEM to predict the behavior of the sample on both particle and packing scale. The main advantages and limits of this approach are finally discussed based on these results and those of previous studies.

  17. High-resolution digital elevation models from single-pass TanDEM-X interferometry over mountainous regions: A case study of Inylchek Glacier, Central Asia

    Science.gov (United States)

    Neelmeijer, Julia; Motagh, Mahdi; Bookhagen, Bodo

    2017-08-01

    This study demonstrates the potential of using single-pass TanDEM-X (TDX) radar imagery to analyse inter- and intra-annual glacier changes in mountainous terrain. Based on SAR images acquired in February 2012, March 2013 and November 2013 over the Inylchek Glacier, Kyrgyzstan, we discuss in detail the processing steps required to generate three reliable digital elevation models (DEMs) with a spatial resolution of 10 m that can be used for glacial mass balance studies. We describe the interferometric processing steps and the influence of a priori elevation information that is required to model long-wavelength topographic effects. We also focus on DEM alignment to allow optimal DEM comparisons and on the effects of radar signal penetration on ice and snow surface elevations. We finally compare glacier elevation changes between the three TDX DEMs and the C-band shuttle radar topography mission (SRTM) DEM from February 2000. We introduce a new approach for glacier elevation change calculations that depends on the elevation and slope of the terrain. We highlight the superior quality of the TDX DEMs compared to the SRTM DEM, describe remaining DEM uncertainties and discuss the limitations that arise due to the side-looking nature of the radar sensor.

  18. Aerial photography flight quality assessment with GPS/INS and DEM data

    Science.gov (United States)

    Zhao, Haitao; Zhang, Bing; Shang, Jiali; Liu, Jiangui; Li, Dong; Chen, Yanyan; Zuo, Zhengli; Chen, Zhengchao

    2018-01-01

    The flight altitude, ground coverage, photo overlap, and other acquisition specifications of an aerial photography flight mission directly affect the quality and accuracy of the subsequent mapping tasks. To ensure smooth post-flight data processing and fulfill the pre-defined mapping accuracy, flight quality assessments should be carried out in time. This paper presents a novel and rigorous approach for flight quality evaluation of frame cameras with GPS/INS data and DEM, using geometric calculation rather than image analysis as in the conventional methods. This new approach is based mainly on the collinearity equations, in which the accuracy of a set of flight quality indicators is derived through a rigorous error propagation model and validated with scenario data. Theoretical analysis and practical flight test of an aerial photography mission using an UltraCamXp camera showed that the calculated photo overlap is accurate enough for flight quality assessment of 5 cm ground sample distance image, using the SRTMGL3 DEM and the POSAV510 GPS/INS data. An even better overlap accuracy could be achieved for coarser-resolution aerial photography. With this new approach, the flight quality evaluation can be conducted on site right after landing, providing accurate and timely information for decision making.

  19. Historic Low Wall Detection via Topographic Parameter Images Derived from Fine-Resolution DEM

    Directory of Open Access Journals (Sweden)

    Hone-Jay Chu

    2017-11-01

    Full Text Available Coral walls protect vegetation gardens from strong winds that sweep across Xiji Island, Taiwan Strait for half the year. Topographic parameters based on light detection and ranging (LiDAR-based high-resolution digital elevation model (DEM provide obvious correspondence with the expected form of landscape features. The information on slope, curvature, and openness can help identify the location of landscape features. This study applied the automatic landscape line detection to extract historic vegetable garden wall lines from a LiDAR-derived DEM. The three rapid processes used in this study included the derivation of topographic parameters, line extraction, and aggregation. The rules were extracted from a decision tree to check the line detection from multiple topographic parameters. Results show that wall line detection with multiple topographic parameter images is an alternative means of obtaining essential historic wall feature information. Multiple topographic parameters are highly related to low wall feature identification. Furthermore, the accuracy of wall feature detection is 74% compared with manual interpretation. Thus, this study provides rapid wall detection systems with multiple topographic parameters for further historic landscape management.

  1. Interferometric SAR Coherence Models for Characterization of Hemiboreal Forests Using TanDEM-X Data

    Directory of Open Access Journals (Sweden)

    Aire Olesk

    2016-08-01

    Full Text Available In this study, four models describing the interferometric coherence of the forest vegetation layer are proposed and compared with the TanDEM-X data. Our focus is on developing tools for hemiboreal forest height estimation from single-pol interferometric SAR measurements, suitable for wide area forest mapping with limited a priori information. The multi-temporal set of 19 TanDEM-X interferometric pairs and the 90th percentile forest height maps are derived from Airborne LiDAR Scanning (ALS, covering an area of 2211 ha of forests over Estonia. Three semi-empirical models along with the Random Volume over Ground (RVoG model are examined for applicable parameter ranges and model performance under various conditions for over 3000 forest stands. This study shows that all four models performed well in describing the relationship between forest height and interferometric coherence. Use of an advanced model with multiple parameters is not always justified when modeling the volume decorrelation in the boreal and hemiboreal forests. The proposed set of semi-empirical models, show higher robustness compared to a more advanced RVoG model under a range of seasonal and environmental conditions during data acquisition. We also examine the dynamic range of parameters that different models can take and propose optimal conditions for forest stand height inversion for operationally-feasible scenarios.

  2. Calibration of micromechanical parameters for DEM simulations by using the particle filter

    Science.gov (United States)

    Cheng, Hongyang; Shuku, Takayuki; Thoeni, Klaus; Yamamoto, Haruyuki

    2017-06-01

    The calibration of DEM models is typically accomplished by trail and error. However, the procedure lacks of objectivity and has several uncertainties. To deal with these issues, the particle filter is employed as a novel approach to calibrate DEM models of granular soils. The posterior probability distribution of the microparameters that give numerical results in good agreement with the experimental response of a Toyoura sand specimen is approximated by independent model trajectories, referred as `particles', based on Monte Carlo sampling. The soil specimen is modeled by polydisperse packings with different numbers of spherical grains. Prepared in `stress-free' states, the packings are subjected to triaxial quasistatic loading. Given the experimental data, the posterior probability distribution is incrementally updated, until convergence is reached. The resulting `particles' with higher weights are identified as the calibration results. The evolutions of the weighted averages and posterior probability distribution of the micro-parameters are plotted to show the advantage of using a particle filter, i.e., multiple solutions are identified for each parameter with known probabilities of reproducing the experimental response.

  3. Calibration of micromechanical parameters for DEM simulations by using the particle filter

    Directory of Open Access Journals (Sweden)

    Cheng Hongyang

    2017-01-01

    Full Text Available The calibration of DEM models is typically accomplished by trail and error. However, the procedure lacks of objectivity and has several uncertainties. To deal with these issues, the particle filter is employed as a novel approach to calibrate DEM models of granular soils. The posterior probability distribution of the microparameters that give numerical results in good agreement with the experimental response of a Toyoura sand specimen is approximated by independent model trajectories, referred as ‘particles’, based on Monte Carlo sampling. The soil specimen is modeled by polydisperse packings with different numbers of spherical grains. Prepared in ‘stress-free’ states, the packings are subjected to triaxial quasistatic loading. Given the experimental data, the posterior probability distribution is incrementally updated, until convergence is reached. The resulting ‘particles’ with higher weights are identified as the calibration results. The evolutions of the weighted averages and posterior probability distribution of the micro-parameters are plotted to show the advantage of using a particle filter, i.e., multiple solutions are identified for each parameter with known probabilities of reproducing the experimental response.

  4. Investigating mixing and segregation using discrete element modelling (DEM) in the Freeman FT4 rheometer.

    Science.gov (United States)

    Yan, Zilin; Wilkinson, Sam K; Stitt, Edmund H; Marigo, Michele

    2016-11-20

    Mixing and segregation in a Freeman FT4 powder rheometer, using binary mixtures with varied particle size ratio and volume fraction, were studied using the Discrete Element Method (DEM). As the blade moves within the particle bed, size induced segregations can occur via a sifting mechanism. A larger particle size ratio and/or a larger volume fraction of large particles lead to a quicker segregation process. A higher particle velocity magnitude can promote the segregation process and the rate for the segregation index increases in the radial direction: from the centre towards the outer layer. In the current DEM simulations, it is shown that the change in flow energy associated with segregation and mixing depends on the choice of frictional input parameters. FT4 is proposed as a potential tool to compare and rank the segregation tendency for particulate materials with distinct differences in flow energy of each component. This is achieved by measuring the flow energy gradient after a number of test cycles for mixing powders with different flow properties. Employing the FT4 dynamic powder characterisation can be advantageous to establish blending performances in an industrial context. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. CFD-DEM simulation of a conceptual gas-cooled fluidized bed nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Lucilla C.; Su, Jian, E-mail: lucillalmeida@gmail.com, E-mail: sujian@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Aguirre, Joao, E-mail: aguirre@rocky-dem.com [Engineering Simulation and Scientific Software (ESSS), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    Several conceptual designs of the fluidized-bed nuclear reactor have been proposed due to its many advantages over conventional nuclear reactors such as PWRs and BWRs. Amongst their characteristics, the enhanced heat transfer and mixing enables a more uniform temperature distribution, reducing the risk of hot-spot and excessive fuel temperature, in addition to resulting in a higher burnup of the fuel. Furthermore, the relationship between the bed height and reactor neutronics turns the coolant flow rate control into a power production mechanism. Moreover, the possibility of removing the fuel by gravity from the movable core in case of a loss-of-cooling accident increases its safety. High-accuracy modeling of particles and coolant flow in fluidized bed reactors is needed to evaluate reliably the thermal-hydraulic efficiency and safety margin. The two-way coupling between solid and fluid can account for high-fidelity solid-solid interaction and reasonable accuracy in fluid calculation and fluid-solid interaction. In the CFD-DEM model, the particles are modeled as a discrete phase, following the DEM approach, whereas the fluid flow is treated as a continuous phase, described by the averaged Navier-Stokes equations on a computational cell scale. In this work, the coupling methodology between Fluent and Rocky is described. The numerical approach was applied to the simulation of a bubbling fluidized bed and the results were compared to experimental data and showed good agreement. (author)

  6. A spheropolygonal-based DEM study into breakage under repetitive compression

    Science.gov (United States)

    Miao, Guien; Alonso-Marroquin, Fernando; Airey, David

    2017-06-01

    Experimental breakage studies have often focused on comparing grading and particle shape data from the beginning and end of a test, but one major advantage of DEM simulations is that, although the data are still discrete, more information on intermediate stages is available. This paper describes a repetitive compression test using a 2D aggregate-based DEM model comprised of spheropolygonal particles (formed by the Minkowski sum of a circle and a polygon, viz. sweeping a circle around the edges of the polygon) that are connected by beams and compares the behaviour with experimental data on the breakage of Barrys Beach carbonate sand. The one-dimensional repetitive compression test was performed on 20 particles—each consisting of over 100 sub-particles—which were generated from the outlines of particles of Barrys Beach carbonate sand. Particle breakage was described through the breakage of beams (particle bonds), allowing the evaluation of changes in the compressibility and grading. It was noted that the simulation compared well with the experimental behaviour of Barrys Beach carbonate sand.

  7. CFD-DEM Simulation of Minimum Fluidisation Velocity in Two Phase Medium

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-09-01

    Full Text Available In this work, CFD-DEM (computational fluid dynamics - discrete element method has been used to model the 2 phase flow composed of solid particle and gas in the fluidised bed. This technique uses the Eulerian and the Langrangian methods to solve fluid and particles respectively. Each particle is treated as a discrete entity whose motion is governed by Newton's laws of motion. The particle-particle and particle-wall interaction is modelled using the classical contact mechanics. The particles motion is coupled with the volume averaged equations of the fluid dynamics using drag law. In fluidised bed, particles start experiencing drag once the fluid is passing through. The solid particles response to it once drag experienced is just equal to the weight of the particles. At this moment pressure drop across the bed is just equal to the weight of particles divide by the cross-section area. This is the first regime of fluidization, also referred as ‘the regime of minimum fluidization’. In this study, phenomenon of minimum fluidization is studied using CFD-DEM simulation with 4 different sizes of particles 0.15 mm, 0.3 mm, 0.6 mm, and 1.2 mm diameters. The results are presented in the form of pressure drop across the bed with the fluid superficial velocity. The achieved results are found in good agreement with the experimental and theoretical data available in literature.

  8. A spheropolygonal-based DEM study into breakage under repetitive compression

    Directory of Open Access Journals (Sweden)

    Miao Guien

    2017-01-01

    Full Text Available Experimental breakage studies have often focused on comparing grading and particle shape data from the beginning and end of a test, but one major advantage of DEM simulations is that, although the data are still discrete, more information on intermediate stages is available. This paper describes a repetitive compression test using a 2D aggregate-based DEM model comprised of spheropolygonal particles (formed by the Minkowski sum of a circle and a polygon, viz. sweeping a circle around the edges of the polygon that are connected by beams and compares the behaviour with experimental data on the breakage of Barrys Beach carbonate sand. The one-dimensional repetitive compression test was performed on 20 particles—each consisting of over 100 sub-particles—which were generated from the outlines of particles of Barrys Beach carbonate sand. Particle breakage was described through the breakage of beams (particle bonds, allowing the evaluation of changes in the compressibility and grading. It was noted that the simulation compared well with the experimental behaviour of Barrys Beach carbonate sand.

  9. A hybrid DEM-SPH model for deformable landslide and its generated surge waves

    Science.gov (United States)

    Tan, Hai; Chen, Shenghong

    2017-10-01

    Reservoir bank landslide and its generated surge waves are catastrophic hazards which may give rise to additional sedimentation, destroy hydraulic structures, and even cause fatalities. Since this process is very complex involving landslide impact, wave generation and propagation, it cannot be well captured with traditional numerical approaches. In this paper, a hybrid DEM-SPH model is presented to simulate landslide and to reproduce its generated surge waves. This model consists of discrete element method (DEM) for solid phase and smoothed particle hydrodynamics (SPH) for fluid phase as well as drag force and buoyancy for solid-fluid interaction. Meanwhile, the δ-SPH algorithm is employed to eliminate spurious numerical noise on the pressure field. Submarine rigid block slide is numerically tested to validate the proposed hybrid model, and the computed wave profiles exhibit a satisfactory agreement with the experiment. The hybrid model is further extended towards the submarine granular deformable slide which generates smaller and less violent surge waves. Kinetic and potential energy of both solid and fluid particle system are extracted to throw a light upon the process of landslide water interaction from an energy perspective. Finally, a sensitivity analysis on particle friction coefficient indicates that the lubrication of the solid particles is another important effect influencing the underwater landslide movement in addition to the drag effect.

  10. 3D DEM study of stick-slip behavior in partly saturated granular materials

    Science.gov (United States)

    Dorostkar, Omid; Johnson, Paul; Guyer, Robert; Marone, Chris; Carmeliet, Jan

    2017-04-01

    In the central part of faults, granular material is produced due to wear called fault gouge. During shearing, the fault gouge stores energy in the course of the stick phase, which can be suddenly released resulting in a stick-slip dynamics. The sudden release of accumulated energy leads to a drop in macroscopic friction coefficient, defined as ratio between shear stress and confining stress and to a sudden increase in kinetic energy of particles. Partial saturation of granular fault gouge with water can alter this dynamic stick-slip behavior. We use 3D discrete element method (DEM) simulations to study stick-slip dynamics in a wet granular fault gouge. The DEM model takes the presence of moisture into account introducing cohesive forces due to the presence of capillary bridges between the particles. We also consider viscous forces resistant to particles motion. Results show that in wet granular gouge, the macroscopic friction level attained during shearing is higher than in the dry state. The cohesive forces due to surface tension and Laplace pressure tend to maintain the contacts longer leading to longer and more stable stick phases, or higher recurrence times between successive slip events. This means that more energy can be stored leading to larger slip events characterized by larger drops in friction coefficient and larger thickness compaction. Our results are in line with experimental results on granular gouge of glass beads.

  11. Experimental study and DEM simulation of granular flow through a new sphere discharge valve

    International Nuclear Information System (INIS)

    Zhang He; Li Tianjin; Huang Zhiyong; Gao Zhi; Qi Weiwei; Bo Hanliang

    2015-01-01

    Experiments and DEM simulation have been conducted to investigate the granular flow through a new type of sphere discharge valve. The new sphere discharge valve was based on the principle of angle of repose. The glass sphere was used in the granular discharge experiments. Experimental results showed that the relation between the averaging sphere discharge mass flow rate and the stroke of the sphere discharge valve were consisted of three zones, i.e. the idle stroke zone, linearly zone and orifice restriction zone. The Beverloo's law was suitable for the granular flow through multi-orifices in the orifice restriction zone. The variation of averaging sphere discharge mass flow rate with the stroke of the sphere discharge valve was described by Beverloo's law with the modification based on the stroke of the sphere discharge valve. DEM simulation results showed that the drained angle of repose during granular flow in the sphere storage vessel remained 23 degrees with different stroke of the sphere discharge valve. (authors)

  12. Landslide Detection in the Carlyon Beach, WA Peninsula: Analysis Of High Resolution DEMs

    Science.gov (United States)

    Fayne, J.; Tran, C.; Mora, O. E.

    2017-12-01

    Landslides are geological events caused by slope instability and degradation, leading to the sliding of large masses of rock and soil down a mountain or hillside. These events are influenced by topography, geology, weather and human activity, and can cause extensive damage to the environment and infrastructure, such as the destruction of transportation networks, homes, and businesses. It is therefore imperative to detect early-warning signs of landslide hazards as a means of mitigation and disaster prevention. Traditional landslide surveillance consists of field mapping, but the process is expensive and time consuming. This study uses Light Detection and Ranging (LiDAR) derived Digital Elevation Models (DEMs) and k-means clustering and Gaussian Mixture Model (GMM) to analyze surface roughness and extract spatial features and patterns of landslides and landslide-prone areas. The methodology based on several feature extractors employs an unsupervised classifier on the Carlyon Beach Peninsula in the state of Washington to attempt to identify slide potential terrain. When compared with the independently compiled landslide inventory map, the proposed algorithm correctly classifies up to 87% of the terrain. These results suggest that the proposed methods and LiDAR-derived DEMs can provide important surface information and be used as efficient tools for digital terrain analysis to create accurate landslide maps.

  13. Erstnachweis von Taiwania, Cryptomeria und Liquidambar aus dem Bitterfelder und Baltischen Bernstein

    Directory of Open Access Journals (Sweden)

    H. Jähnichen

    1998-01-01

    Full Text Available Aus dem untermiozänen Bernstein von Bitterfeld (Sachsen-Anhalt werden erstmalig ein strukturzeigender Zweig von Taiwania schaeferi, ein isoliertes Nadel-Fragment von Cryptomeria sp. sowie ein Fruchtstand von Liquidambar europaea beschrieben. Außerdem muß “Widdringtonites oblongifolius” (Goeppert & Menge Caspary & Klebs 1906/07 pro parte aus dem obereozänen Baltischen Bernstein nach morphologisch-anatomischen Merkmalskomplexen ebenfalls zu Taiwania schaeferi gestellt werden. “Enormicutis eoconferta” — aff. Cryptomeria spec. (Schneider 1986 aus der obereozänen Braunkohle von Nordwestsachsen muß nach morphologisch-anatomischen Details zu Athrotaxis couttsiae (Heer Gardner revidiert werden. First record of Taiwania, Cryptomeria and Liquidambar from Bitterfeld and Baltic amber A structure-bearing twig of Taiwania schaeferi, an isolated needle-fragment of Cryptomeria spec. as also an aggregate fruit of Liquidambar europaea are firstly described from the Lower Miocene amber of Bitterfeld (Saxony-Anhalt. Moreover “Widdringtonites oblongifolius” (Goeppert & Menge Caspary & Klebs 1906/07 p.p. from the Upper Eocene Baltic amber after morphological-anatomical features must be also assigned to Taiwania schaeferi. “Enormicutis eoconferta” — aff. Cryptomeria sp. (Schneider 1986 from the Upper Eocene brown-coal of North Western Saxony after morphological-anatomical details must be revised to Athrotaxis couttsiae (Heer Gardner. doi:10.1002/mmng.19980010112

  14. Toward the modeling of combustion reactions through discrete element method (DEM) simulations

    Science.gov (United States)

    Reis, Martina Costa; Alobaid, Falah; Wang, Yongqi

    2018-03-01

    In this work, the process of combustion of coal particles under turbulent regime in a high-temperature reaction chamber is modeled through 3D discrete element method (DEM) simulations. By assuming the occurrence of interfacial transport phenomena between the gas and solid phases, one investigates the influence of the physicochemical properties of particles on the rates of heterogeneous chemical reactions, as well as the influence of eddies present in the gas phase on the mass transport of reactants toward the coal particles surface. Moreover, by considering a simplistic chemical mechanism for the combustion process, thermochemical and kinetic parameters obtained from the simulations are employed to discuss some phenomenological aspects of the combustion process. In particular, the observed changes in the mass and volume of coal particles during the gasification and combustion steps are discussed by emphasizing the changes in the chemical structure of the coal. In addition to illustrate how DEM simulations can be used in the modeling of consecutive and parallel chemical reactions, this work also shows how heterogeneous and homogeneous chemical reactions become a source of mass and energy for the gas phase.

  15. DEM study of granular flow around blocks attached to inclined walls

    Science.gov (United States)

    Samsu, Joel; Zhou, Zongyan; Pinson, David; Chew, Sheng

    2017-06-01

    Damage due to intense particle-wall contact in industrial applications can cause severe problems in industries such as mineral processing, mining and metallurgy. Studying the flow dynamics and forces on containing walls can provide valuable feedback for equipment design and optimising operations to prolong the equipment lifetime. Therefore, solids flow-wall interaction phenomena, i.e. induced wall stress and particle flow patterns should be well understood. In this work, discrete element method (DEM) is used to study steady state granular flow in a gravity-fed hopper like geometry with blocks attached to an inclined wall. The effects of different geometries, e.g. different wall angles and spacing between blocks are studied by means of a 3D DEM slot model with periodic boundary conditions. The findings of this work include (i) flow analysis in terms of flow patterns and particle velocities, (ii) force distributions within the model geometry, and (iii) wall stress vs. model height diagrams. The model enables easy transfer of the key findings to other industrial applications handling granular materials.

  16. Ethik und Politik im Anschluss an Levinas – Zwischen dem einen und den vielen Anderen?

    Directory of Open Access Journals (Sweden)

    Buddeberg Eva

    2016-07-01

    Full Text Available Wird in philosophischen Diskussionen auf Emmanuel Levinas Bezug genommen, bleibt es zumindest in einigen Theoriekontexten häufig bei dem Verweis auf den „Anderen“, dem wir die Moral schulden, gelten doch seine Schriften immer noch als metaphysisch aufgeladen und in ihrer Radikalität als unplausibel. Weitgehend außer Acht gelassen wird dabei, wie Levinas sich dazu äußert, dass wir in der Welt nie nur mit einem, sondern mit vielen Anderen leben und somit vor der Frage stehen, wie wir diesen allen gerecht werden können. Auch dass für Levinas diese Frage nicht mehr in den Bereich der Ethik, sondern in das Feld der Politik gehört, wird entsprechend oft nicht weiter reflektiert. Um das Verhältnis zwischen Ethik und Politik bei Levinas im Hinblick auf einen Dialog mit anderen Theorieansätzen näher zu beleuchten, werde ich zunächst wichtige Grundannahmen seiner Philosophie in Erinnerung rufen. In einem zweiten Schritt werde ich überlegen, inwiefern die Bezugnahme auf seine Arbeiten für andere moralphilosophische Ansätze fruchtbar sein könnte. Schließlich werde ich darlegen, inwiefern auch für an Levinas anknüpfende Theorien eine Öffnung hin zu anderen Philosophietraditionen sinnvoll ist.

  17. Parallel Resolved Open Source CFD-DEM: Method, Validation and Application

    Directory of Open Access Journals (Sweden)

    A. Hager

    2014-03-01

    Full Text Available In the following paper the authors present a fully parallelized Open Source method for calculating the interaction of immersed bodies and surrounding fluid. A combination of computational fluid dynamics (CFD and a discrete element method (DEM accounts for the physics of both the fluid and the particles. The objects considered are relatively big compared to the cells of the fluid mesh, i.e. they cover several cells each. Thus this fictitious domain method (FDM is called resolved. The implementation is realized within the Open Source framework CFDEMcOupling (www.cfdem.com, which provides an interface between OpenFOAM® based CFD-solvers and the DEM software LIGGGHTS (www.liggghts.com. While both LIGGGHTS and OpenFOAM® were already parallelized, only a recent improvement of the algorithm permits the fully parallel computation of resolved problems. Alongside with a detailed description of the method, its implementation and recent improvements, a number of application and validation examples is presented in the scope of this paper.

  18. DEM study of granular flow around blocks attached to inclined walls

    Directory of Open Access Journals (Sweden)

    Samsu Joel

    2017-01-01

    Full Text Available Damage due to intense particle-wall contact in industrial applications can cause severe problems in industries such as mineral processing, mining and metallurgy. Studying the flow dynamics and forces on containing walls can provide valuable feedback for equipment design and optimising operations to prolong the equipment lifetime. Therefore, solids flow-wall interaction phenomena, i.e. induced wall stress and particle flow patterns should be well understood. In this work, discrete element method (DEM is used to study steady state granular flow in a gravity-fed hopper like geometry with blocks attached to an inclined wall. The effects of different geometries, e.g. different wall angles and spacing between blocks are studied by means of a 3D DEM slot model with periodic boundary conditions. The findings of this work include (i flow analysis in terms of flow patterns and particle velocities, (ii force distributions within the model geometry, and (iii wall stress vs. model height diagrams. The model enables easy transfer of the key findings to other industrial applications handling granular materials.

  19. Constructing Palaeo-DEMs in landscape evolution: example of the Geren catchment, Turkey

    Science.gov (United States)

    van Gorp, Wouter; Schoorl, Jeroen M.; Veldkamp, Tom; Maddy, Darrel; Demir, Tuncer; Aytac, Serdar

    2017-04-01

    How to reconstruct the past landscape and how does this influence your modelling results? This is an important paradigma in the soilscape and landscape evolution modelling community. Here an example of Turkey will be presented where a 300 ka LEM simulation requested to the thoroughly think about the initial landscape as an important input. What information can be used to know the morphology of a landscape 300 ka ago? The Geren catchment, a tributary of the upstream Gediz river near Kula, Turkey, has been influenced by base level changes during the Late Pleistocene and Holocene. Different lavaflows have blocked the Gediz and Geren river several times over in the timespan of the last 300 ka -200 Ka and in the recent Holocene. The heavily dissected Geren catchment shows a landscape evolution which is more complex than just a reaction on these base level changes. The steps and inputs of the palaeo DEM reconstruction will be presented and the modelling results will be presented. Keywords: Digital Elevation Model, Palaeo DEMs, Numerical modelling

  20. Programa para cuidadores de idosos com demência: relato de experiência

    Directory of Open Access Journals (Sweden)

    Ana Karine Ramos Brum

    2013-08-01

    Full Text Available Trata-se de um relato de experiência sobre o projeto PRó-CUIDEM, com encontros coordenados por enfermeiras docentes em Niterói-RJ. Os resultados estão centrados nos cuidadores que necessitam de orientações, expressas em reuniões do grupo, onde as dúvidas são esclarecidas, fazendo com que eles se sintam menos ansiosos e mais dispostos a cuidar do idoso, com compreensão de seu problema de saúde e, principalmente, cuidar da própria saúde. Concluímos que o cuidar do idoso com demência é uma tarefa difícil quando não há suporte e orientação, sendo fundamental o cuidado de enfermagem na forma de orientações e a sua divulgação melhorando a qualidade de vida dos cuidadores e, por consequência, a dos idosos com demência.

  1. Comparison Between Topographic Expression of RADARSAT and DEM in Simpang Pulai to Pos Selim, Malaysia

    Directory of Open Access Journals (Sweden)

    M.F.Ramli

    2010-01-01

    Full Text Available Radar and digital elevation model had been utilised in many structural studies. The main objective of this study is to compare the RADARSAT and digital elevation model for lineament interpretation which probably represent the main joints or faults along the Simpang Pulai to Pos Selim highway, Malaysia. These joints and faults may influence the instability along the highway. Manual comparison in terms of topographical aspect was undertaken between RADARSAT with 25 m spatial resolution and digital elevation model derived from 20 m contour interval of the topographical map. The previously interpreted lineaments of more than 2 km in the study area was draped over the RADARSAT and digital elevation model to compared whether the lineament concurred with the topographical representation. The interpreted lineaments were derived from Landsat TM of 1990 and 2002, where the DEM had been utilised in the negative lineament determination. It is concluded that the application RADARSAT is not very useful in terms of topographical expression in the structural geological interpretation for the study area compared to DEM derived from contour data. Further work is suggested before any conclusion can be confidently derived.

  2. „Das zweite Leben“ der Theresienstadt-Filme nach dem Zweiten Weltkrieg

    Directory of Open Access Journals (Sweden)

    Eva Strusková

    2016-05-01

    Full Text Available Das Filmmaterial, das zwischen 1942 und 1945 im Ghetto von Theresienstadt entstanden ist, galt lange Zeit als verschollen. Archivfunde und  Ergebnisse historischer Untersuchungen der letzten Jahrzehnte ermöglichen es erstmals, die Wege der einzelnen Filmfragmente nach 1945 in verschiedene internationale Archive nachzuvollziehen. Dokumente, die vor Kurzem im Archiv der ehemaligen tschechoslowakischen Staatssicherheit  StB (heute: Archiv bezpečnostních složek in Prag aufgetaucht sind, wurden zu einer neuen Informationsquelle über die Produktion des umstrittenen Propagandafilms Theresienstadt. Ein Dokumentarfilm aus dem jüdischen Siedlungsgebiet (1944-45. Sie geben Aufschluss über den  Prozess um den inoffiziellen Verkaufvon Bestandteilen des Films nach Westdeutschland, der Mitte der 1960er in Prag stattfand. In diesem Artikel wird die Nachkriegsgeschichte der Aufnahmen aus dem Ghetto von Theresienstadt, die eine der Schlüsselquellen für historische Studien und Veröffentlichungen über den Holocaust geworden sind, anhand von Archivstudien rekonstruiert. Der Artikel enthält  zwei Schautafeln zur Provenienz und Historie der Fragmente, die aufzeigen, wie und wann sie in europäische und israelische Archive gelangt sind.

  3. Satisfação sexual na demência Sexual satisfaction in dementia

    Directory of Open Access Journals (Sweden)

    Marcela Moreira Lima Nogueira

    2013-01-01

    Full Text Available CONTEXTO: A demência pode resultar em comprometimento da intimidade e sexualidade de casais idosos. OBJETIVOS: Avaliar alterações na atividade sexual, bem como os fatores de satisfação e/ou insatisfação sexual de casais nos quais um dos parceiros possua demência. MÉTODO: Busca nas bases de dados ISI, PubMed/Medline e SciELO de artigos sobre sexualidade na demência, entre janeiro de 1990 e março de 2012, utilizando as palavras-chave: "demência", "satisfação sexual", "intimidade" e "sexualidade". RESULTADOS: Foram encontrados 12 artigos. A sobrecarga de cuidados e a alteração de papéis na relação conjugal foram consideradas as principais causas para o declínio da atividade sexual. A disfunção erétil em pacientes e cônjuges, a capacidade decisória para o consentimento da relação sexual por parte do paciente demenciado e os problemas referentes à idade e à saúde (física e emocional do cônjuge e/ou paciente foram os fatores associados à insatisfação sexual. CONCLUSÃO: A intimidade e a atividade sexual dos casais em que um dos parceiros é portador de demência são influenciadas negativamente pela relação de cuidados decorrente da doença e pela sobrecarga dos cônjuges. Por outro lado, a atividade sexual pode ser positivamente substituída por demonstrações de carinho e empatia entre os cônjuges.BACKGROUND: Dementia may result on impairment in intimacy and sexuality of elderly couples. OBJECTIVES: Evaluate changes in sexual activity, as well as the factors which cause sexual satisfaction and/or dissatisfaction in couples in which one of the partners has dementia. METHOD: A search at ISI, PubMed/Medline and SciELO was made for articles about sexuality in dementia, from January 1990 to March 2012, using the keywords: "dementia", "sexual satisfaction", "intimacy" and "sexuality". RESULTS: Twelve articles were selected. The burden of care and the change of roles in couples' relationship were the main reasons for

  4. BOREAS HYD-8 DEM Data Over the NSA-MSA and SSA-MSA in the UTM Projection

    Science.gov (United States)

    Wang, Xue-Wen; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Band, L. E.; Smith, David E. (Technical Monitor)

    2000-01-01

    The BOREAS HYD-8 team focused on describing the scaling behavior of water and carbon flux processes at local and regional scales. These DEMs were produced from digitized contours at a cell resolution of 100 meters. Vector contours of the area were used as input to a software package that interpolates between contours to create a DEM representing the terrain surface. The vector contours had a contour interval of 25 feet. The data cover the BOREAS MSAs of the SSA and NSA and are given in a UTM map projection. Most of the elevation data from which the DEM was produced were collected in the 1970s or 1980s. The data are stored in binary, image format files. The data files are available on a CD-ROM (see document number 20010000884) or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  5. Fusion of photogrammetric and photoclinometric information for high-resolution DEMs from Mars in-orbit imagery

    Science.gov (United States)

    Douté, S.; Jiang, C.

    2017-09-01

    High-resolution Digital Elevation Models (DEMs) of the Martian surface are instrumental for studying the red planet : characterizing geological objects, generating synthetic images, normalizing illumination conditions on images, and modeling local meteorology. Our work addresses the problem of producing DEMs for regions of interest on Mars using available in-orbit imagery, typically ≈1000 km2 in area, while insuring a ≈10 meters vertical accuracy and a spatial accuracy which is comparable to that of the imagery. A method is proposed that combines photogrammetric and photoclinometric approaches in order to retain their mutual advantages. According to experiments using Mars Reconnaissance Orbiter Context Camera (CTX) images, the proposed method is indeed able to produce DEMs satisfying the previous requirements, with less artifacts, better surface continuity, and sharper details than the photogrammetric method when it is used alone.

  6. Optimizing landslide susceptibility zonation: Effects of DEM spatial resolution and slope unit delineation on logistic regression models

    Science.gov (United States)

    Schlögel, R.; Marchesini, I.; Alvioli, M.; Reichenbach, P.; Rossi, M.; Malet, J.-P.

    2018-01-01

    We perform landslide susceptibility zonation with slope units using three digital elevation models (DEMs) of varying spatial resolution of the Ubaye Valley (South French Alps). In so doing, we applied a recently developed algorithm automating slope unit delineation, given a number of parameters, in order to optimize simultaneously the partitioning of the terrain and the performance of a logistic regression susceptibility model. The method allowed us to obtain optimal slope units for each available DEM spatial resolution. For each resolution, we studied the susceptibility model performance by analyzing in detail the relevance of the conditioning variables. The analysis is based on landslide morphology data, considering either the whole landslide or only the source area outline as inputs. The procedure allowed us to select the most useful information, in terms of DEM spatial resolution, thematic variables and landslide inventory, in order to obtain the most reliable slope unit-based landslide susceptibility assessment.

  7. The EVE plus RHESSI DEM for Solar Flares, and Implications for Residual Non-Thermal X-Ray Emission

    Science.gov (United States)

    McTiernan, James; Caspi, Amir; Warren, Harry

    2016-05-01

    Solar flare spectra are typically dominated by thermal emission in the soft X-ray energy range. The low energy extent of non-thermal emission can only be loosely quantified using currently available X-ray data. To address this issue, we combine observations from the EUV Variability Experiment (EVE) on-board the Solar Dynamics Observatory (SDO) with X-ray data from the Reuven Ramaty High Energy Spectroscopic Imager (RHESSI) to calculate the Differential Emission Measure (DEM) for solar flares. This improvement over the isothermal approximation helps to resolve the ambiguity in the range where the thermal and non-thermal components may have similar photon fluxes. This "crossover" range can extend up to 30 keV.Previous work (Caspi et.al. 2014ApJ...788L..31C) concentrated on obtaining DEM models that fit both instruments' observations well. For this current project we are interested in breaks and cutoffs in the "residual" non-thermal spectrum; i.e., the RHESSI spectrum that is left over after the DEM has accounted for the bulk of the soft X-ray emission. As in our earlier work, thermal emission is modeled using a DEM that is parametrized as multiple gaussians in temperature. Non-thermal emission is modeled as a photon spectrum obtained using a thin-target emission model ('thin2' from the SolarSoft Xray IDL package). Spectra for both instruments are fit simultaneously in a self-consistent manner.For this study, we have examined the DEM and non-thermal resuidual emission for a sample of relatively large (GOES M class and above) solar flares observed from 2011 to 2014. The results for the DEM and non-thermal parameters found using the combined EVE-RHESSI data are compared with those found using only RHESSI data.

  8. Influence of different DEMs on the quality of the InSAR results: case study over Bankya and Mirovo areas

    Science.gov (United States)

    Nikolov, Hristo; Atanasova, Mila

    2017-10-01

    One of the key input parameters in obtaining end products from SAR data is the DEM used during their processing. This holds true especially when persistent scatterers InSAR method should be applied for example to study slow moving landslides or subsidence. Since nowadays most of the raw SAR data are of space borne origin for their correct processing to high precision products for relatively small areas with centimeter accuracy a DEM taking into account the particularities of the local topography is needed. Most of the DEMs used by the SAR processing software such as SRTM or ASTER are obtained by the same type of instrument and present some disagreements with height information acquired by leveling measurements or other geodetic means. This was the motivation for initiating this research - to prove the need of creating and using local DEM in SAR data processing at small scale and to check what the magnitude of the discrepancy between final InSAR products is in both cases where SRTM/ASTER and local DEM has been used. In addition investigated were two scenarios for SAR data processing - one with small baseline between image pairs and one having large baseline image pairs - in order to find out in which case local DEM has bigger impact. In course of this study two reference areas were considered - Bankya village near Sofia (SW region of Bulgaria) and Mirovo salt extraction site (NE region of Bulgaria). The reason those areas were selected lies in the high number of landslides registered and monitored by the competent authorities in the mentioned locations. The significance of the results obtained is witnessed by the fact that both sites we used have been included as reference sites for Bulgaria in the PanGeo EU funded project dealing with delivering information regarding ground instability geohazard as areas prone to subsidence of natural and manmade origin. In the said project largest part of the information has been extracted from Envisat SAR data, but now this

  9. Demências vasculares: crítica sobre critério diagnóstico atual

    OpenAIRE

    Francisco Carlos de Andrade

    2007-01-01

    Demência vascular compreende um declínio cognitivo global, atribuível ao efeito cumulativo das doenças vasculares cerebrais. Como resultado dos danos cerebrovasculares focais, são sucessivamente perdidas as sutis múltiplas habilidades cognitivas, inclusive, memória. Nossa compreensão da demência vascular tem evoluído através dos tempos, em parte devido à possibilidade de seguir as alterações pelos exames de imagens radiológicas e também, através do entendimento da organização neuropsicológica...

  10. Semi-automated extraction of landslides in Taiwan based on SPOT imagery and DEMs

    Science.gov (United States)

    Eisank, Clemens; Hölbling, Daniel; Friedl, Barbara; Chen, Yi-Chin; Chang, Kang-Tsung

    2014-05-01

    The vast availability and improved quality of optical satellite data and digital elevation models (DEMs), as well as the need for complete and up-to-date landslide inventories at various spatial scales have fostered the development of semi-automated landslide recognition systems. Among the tested approaches for designing such systems, object-based image analysis (OBIA) stepped out to be a highly promising methodology. OBIA offers a flexible, spatially enabled framework for effective landslide mapping. Most object-based landslide mapping systems, however, have been tailored to specific, mainly small-scale study areas or even to single landslides only. Even though reported mapping accuracies tend to be higher than for pixel-based approaches, accuracy values are still relatively low and depend on the particular study. There is still room to improve the applicability and objectivity of object-based landslide mapping systems. The presented study aims at developing a knowledge-based landslide mapping system implemented in an OBIA environment, i.e. Trimble eCognition. In comparison to previous knowledge-based approaches, the classification of segmentation-derived multi-scale image objects relies on digital landslide signatures. These signatures hold the common operational knowledge on digital landslide mapping, as reported by 25 Taiwanese landslide experts during personal semi-structured interviews. Specifically, the signatures include information on commonly used data layers, spectral and spatial features, and feature thresholds. The signatures guide the selection and implementation of mapping rules that were finally encoded in Cognition Network Language (CNL). Multi-scale image segmentation is optimized by using the improved Estimation of Scale Parameter (ESP) tool. The approach described above is developed and tested for mapping landslides in a sub-region of the Baichi catchment in Northern Taiwan based on SPOT imagery and a high-resolution DEM. An object

  11. Sediment micromechanics in sheet flows induced by asymmetric waves: A CFD-DEM study

    Science.gov (United States)

    Sun, Rui; Xiao, Heng

    2016-11-01

    Understanding the sediment transport in oscillatory flows is essential to the investigation of the overall sediment budget for coastal regions. This overall budget is crucial for the prediction of the morphological change of the coastline in engineering applications. Since the sediment transport in oscillatory flows is dense particle-laden flow, appropriate modeling the particle interaction is critical. Although traditional two-fluid approaches have been applied to the study of sediment transport in oscillatory flows, the approaches do not capture the interaction of the particles. The study of the motion of individual sediment particles and their micromechanics (e.g., packing and contact force) in oscillatory flows is still lacking. In this work, a parallel CFD-DEM solver SediFoam that can model the inter-particle collision is applied to study the granular micromechanics of sediment particles in oscillatory flows. The results obtained from the CFD-DEM solver are validated by using the experimental data of coarse and medium sands. The comparison with experimental results suggests that the flow velocity, the sediment flux and the net sediment transport rate predicted by SediFoam are satisfactory. Moreover, the micromechanic quantities of the sediment bed are presented in detail, including the Voronoi concentration, the coordination number, and the particle interaction force. It is demonstrated that the variation of these micromechanic quantities at different phases in the oscillatory cycle is significant, which is due to different responses of the sediment bed. To investigate the structural properties of the sediment bed, the correlation of the Voronoi volume fraction and coordination number is compared to the results from the fluidized bed simulations. The consistency in the comparison indicates the structural micromechanics of sediment transport and fluidized bed are similar despite the differences in flow patterns. From the prediction of the CFD-DEM model, we

  12. Muenstraia, ein neues Rugosa-Genus (Anthozoa aus dem Obersilur und Unterdevon

    Directory of Open Access Journals (Sweden)

    D. Weyer

    2001-01-01

    Full Text Available Muenstraia n. gen. ist eine der ältesten ahermatypischen Rugosa (Subordo Cyathaxoniina und umfasst neben der Typusart Muenstraia franconica n. sp. (Ludlovium, Elbersreuther Orthoceratitenkalk, Frankenwald drei weitere Arten: Muenstraia squarrosa (Sutherland, 1965 (unteres Ludlovium, Henryhouse-Formation, Oklahoma, Muenstraia sp. (oberes Lochkovium, Yukon-Gebiet, Muenstraia thuringica n. sp. (Pragium, Thüringisches Schiefergebirge und Tafilalt. Die Gattung kann von dem isolierten, nur aus Xinjiang bekannten Protozaphrentis Yü, 1957 des hohen Mittelordoviz abgeleitet werden; wichtige Deszendenten im Ludlovian sind Laccophyllum Simpson, 1900 und Sutherlandinia Weyer, 1972. Der Bauplan entspricht dem seit Schindewolf (1931 traditionellen Konzept der Gattung Petraia Münster, 1839, die aber nach Revision (Weyer 2000 ihrer wahren Typusart Petraia decussata Münster, 1839 aus dem oberen Famennium einer anderen Entwicklungsreihe angehört (Neaxoninae Hill, 1981, jetzt Petraiidae Koninck, 1872. Für die dadurch namenlos gewordene Familia "Petraiidae" (etwa sensu Hill 1981 werden die bisher als Synonym ruhenden Protozaphrentidae Ivanovskiy, 1959 verfügbar, denen noch Duncanella Nicholson, 1874 sowie die Sutherlandiniinae Weyer, 1972 und die Ditoecholasmatinae Sutherland, 1965 zugeordnet sind. Muenstraia, a new genus of Rugosa (Anthozoa from the Late Silurian and Early Devonian The new taxon, one of the most ancient members of the ahermatypic suborder Cyathaxoniina, includes the type species Muenstraia franconica n. sp. (Ludlovian, Elbersreuth Orthoceratites-Limestone Formation. Upper Franconia, Germany and three further species: Muenstraia squarrosa (Sutherland, 1965 (lower Ludlovian, Henryhouse Formation, Oklahoma, USA, Muenstraia sp. (upper Lochkovian, Yukon Territories, Canada. Muenstraia thuringica n. sp. (middle/upper Pragian, Tentaculitid Limestone Formation, Thuringian Mountains, Germany, and middle Pragian, Tafilalt, Morocco. The genus

  13. Holocene palaeoDEMs for lowland coastal and delta plain landscape reconstructions

    Science.gov (United States)

    Cohen, Kim M.; Koster, Kay; Pierik, Harm-Jan; Van der Meulen, Bas; Hijma, Marc; Schokker, Jeroen; Stafleu, Jan

    2017-04-01

    Geological mapping of Holocene deposits of coastal plains, such as that of The Netherlands can reach high resolution (dense population, diverse applied usage) and good time control (14C dating, archaeology). The next step is then to create time sliced reconstructions for stages in the Holocene, peeling of the subrecent and exposing past relief situation. This includes winding back the history of sea-level rise and delta progradation etc. etc. So far, this has mainly be done as 2D series of landscape maps, or as sea-level curve age-depth plots. In the last decade, academic and applied projects at Utrecht University, TNO Geological Survey of The Netherlands and Deltares have developed palaeoDEMs for the Dutch low lands, that are a third main way of showing coastal plain evolution. Importantly, we produce two types of palaeoDEMs: (1) geological surface mapping using deposit contacts from borehole descriptions (and scripted 3D processing techniques - e.g. Van der Meulen et al. 2013) and (2) palaeogroundwater surfaces, using sea-level and inland water-level index-points (and 3D kriging interpolations - e.g. Koster et al. 2016). The applications for the combined palaeoDEMs range from relative sea-level rise mapping and assessment of variation in rate of GIA across the coastal plain, to quantification of soft soil deformation, to analysis of pre-embankment extreme flood levels. Koster, K., Stafleu, J., & Cohen, K.M. (2016). Generic 3D interpolation of Holocene base-level rise and provision of accommodation space, developed for the Netherlands coastal plain and infilled palaeovalleys. Basin Research. DOI 10.1111/bre.12202 Van der Meulen, M.J., Doornenbal, J.C., Gunnink, J.L., Stafleu, J., Schokker, J., Vernes, R.W., Van Geer, F.C., Van Gessel, S.F., Van Heteren, S., Van Leeuwen, R.J.W. & Bakker, M.A.J. (2013). 3D geology in a 2D country: perspectives for geological surveying in the Netherlands. Netherlands Journal of Geosciences, 92, 217-241. DOI 10.1017/S0016774600000184

  14. DEM investigation on characteristics of rolling resistance for modelling particle shape

    Science.gov (United States)

    Zhou, Lunlun; Chu, Xihua; Xu, Yuanjie

    2017-06-01

    To examine the capability of rolling resistance to model the effects of particle shape, two sets of samples, composed of binary clumped particles and circular particles with rolling resistance, are tested in DEM simulation. The coefficient of rolling friction is estimated based on the energy dissipation. The effects of rolling resistance and particle shape on the shear strength, deformation behavior and non-coaxiality are compared. The numerical results show that rolling resistance reproduces well the effect of particle shape on the peak strength. However, other macro-properties, such as residual strength, elasticity modulus, poisson's ratio, dilatancy and non-coaxiality, introduced by rolling resistance both exist certain differences compared with the effect of particle shape. The discrepancies is thought to be due to the increasing compressibility of samples as the particle shape becomes more elongated, which cannot be reproduced by increasing rolling friction.

  15. Efficient Voronoi volume estimation for DEM simulations of granular materials under confined conditions

    Science.gov (United States)

    Frenning, Göran

    2015-01-01

    When the discrete element method (DEM) is used to simulate confined compression of granular materials, the need arises to estimate the void space surrounding each particle with Voronoi polyhedra. This entails recurring Voronoi tessellation with small changes in the geometry, resulting in a considerable computational overhead. To overcome this limitation, we propose a method with the following features:•A local determination of the polyhedron volume is used, which considerably simplifies implementation of the method.•A linear approximation of the polyhedron volume is utilised, with intermittent exact volume calculations when needed.•The method allows highly accurate volume estimates to be obtained at a considerably reduced computational cost. PMID:26150975

  16. Simulation of Bridging at the Static Surface Filtration by CFD-DEM Coupling

    Science.gov (United States)

    Hund, David; Antonyuk, Sergiy; Ripperger, Siegfried

    2017-06-01

    To achieve a better understanding of the bridging mechanism at the static surface filtration, simulations of particle deposition at a three-dimensional pore model of a filter were performed. The simulations are used to investigate the total filter resistance, which results from interferences between filter medium, particles and fluid. Thereby a CFD (Computational Fluid Dynamics) method for flow simulation was coupled with a Discrete Element Method (DEM) which calculates the particle interactions. The results show that a built particle bridge influences the flow through an unclosed pore. It was concluded that bridging of open pores is hindered at high velocities of approach caused by increasing percentage of closed pores. Moreover, it could be shown, that the total filter resistance depends on the approaching velocity and shape of particles.

  17. Numerical study on gas-solid flow in CBFB based on TFM-DEM hybrid model

    Science.gov (United States)

    Zhang, Tianyu; Zhao, Zhenning; Zhu, Xianran; Cheng, Liang; Liu, Gaojun

    2017-01-01

    This thesis aims at the TFM-DEM hybrid model, taking advantage of open source software MFIX, and takes gas-solid flow process in coal beneficiation fluidized bed (CBFB) as object of research. In gas-solid flow of the coal beneficiation fluidized bed, different diameters of coal/gangue particles are investigated and the existence of effective particle diameter in this apparatus is validated. The coal back mixing phenomenon due to the drag effect of rising bubble in the bed is captured from the particle level in hybrid model, and the time to reach balance in different diameters of coal/gangue particle is compared, which provides the reference for future applications of hybrid model.

  18. Simulation of Bridging at the Static Surface Filtration by CFD-DEM Coupling

    Directory of Open Access Journals (Sweden)

    Hund David

    2017-01-01

    Full Text Available To achieve a better understanding of the bridging mechanism at the static surface filtration, simulations of particle deposition at a three-dimensional pore model of a filter were performed. The simulations are used to investigate the total filter resistance, which results from interferences between filter medium, particles and fluid. Thereby a CFD (Computational Fluid Dynamics method for flow simulation was coupled with a Discrete Element Method (DEM which calculates the particle interactions. The results show that a built particle bridge influences the flow through an unclosed pore. It was concluded that bridging of open pores is hindered at high velocities of approach caused by increasing percentage of closed pores. Moreover, it could be shown, that the total filter resistance depends on the approaching velocity and shape of particles.

  19. Simulation of Hydraulic and Natural Fracture Interaction Using a Coupled DFN-DEM Model

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J.; Huang, H.; Deo, M.

    2016-03-01

    The presence of natural fractures will usually result in a complex fracture network due to the interactions between hydraulic and natural fracture. The reactivation of natural fractures can generally provide additional flow paths from formation to wellbore which play a crucial role in improving the hydrocarbon recovery in these ultra-low permeability reservoir. Thus, accurate description of the geometry of discrete fractures and bedding is highly desired for accurate flow and production predictions. Compared to conventional continuum models that implicitly represent the discrete feature, Discrete Fracture Network (DFN) models could realistically model the connectivity of discontinuities at both reservoir scale and well scale. In this work, a new hybrid numerical model that couples Discrete Fracture Network (DFN) and Dual-Lattice Discrete Element Method (DL-DEM) is proposed to investigate the interaction between hydraulic fracture and natural fractures. Based on the proposed model, the effects of natural fracture orientation, density and injection properties on hydraulic-natural fractures interaction are investigated.

  20. Zur Rekonstruktion einer Typologie jugendlichen Medienhandelns gemäß dem Leitbild der Triangulation

    Directory of Open Access Journals (Sweden)

    Klaus Peter Treumann

    2017-09-01

    Full Text Available Die im Folgenden dargestellten Ergebnisse sind im Rahmen des von der DFG geförderten Forschungsprojekts „Eine Untersuchung zum Mediennutzungsverhalten 12- bis 20-Jähriger und zur Entwicklung von Medienkompetenz im Jugendalter“ entstanden, das gemeinsam von Klaus Peter Treumann, Uwe Sander und Dorothee Meister geleitet wird. Das Forschungsprojekt untersucht das Medienhandeln Jugendlicher sowohl hinsichtlich Neuer als auch alter Medien. Zum einen fragen wir dabei nach den Ausprägungen von Medienkompetenz in verschiedenen Dimensionen und zum anderen konzentrieren wir uns auf die Entwicklung einer empirisch fundierten Typologie jugendlichen Medienhandelns. Methodologisch ist die Untersuchung an dem Leitbild der Triangulation orientiert und kombiniert qualitative und quantitative Zugänge zum Forschungsfeld in Form von Gruppendiskussionen, leitfadengestützten Einzelinterviews und einer Repräsentativerhebung.

  1. Bestimmung der Mas'se des neutralen Bs-Mesons mit dem ALEPH-Experiment

    CERN Document Server

    Stehle, M

    2001-01-01

    Gegenstand der vorliegenden Arbeit ist die Bestimmung der Masse des neutralen Bs-Mesons. Dazu wurden B~-Mesonen in den beiden Zerfallskanalen B~ -+ J/W P und B~ -+ W(2S) P rekonstruiert, wobei die Subresonanzen in den Zerfallsmoden J /w -+ l+ l-, W(2S) -+ l+ l- und P -+ K+ K- untersucht wurden. Diese beiden Kanale werden auf Grund ihrer eindeutigen Signatur auch als "goldene Kanale" bezeichnet und eignen sich deshalb sehr gut fur eine exklusive Rekonstruktion, wie sie hier angewendet wurde. Grundlage der Analyse waren ca. 4 Millionen hadronische ZO-Zerfalle, die in den Jahren 1991 1995 mit dem ALEPH-Detektor am e+e--Speicherring LEP am CERN aufgezeichnet wurden. Die zwischenzeitliche Reprozessierung der Daten ermoglichte eine prazisere und effizientere Rekonstruktion als das in fruheren Messungen der Fall war. Wegen der niedrigen Verzweigungsverhaltnisse der untersuchten Zerfallsmoden wurden nur wenige einzelne Ereignisse in den Daten erwartet. Die selektierten Kandidaten wurden durch Schnitte in mehreren Ere...

  2. Using TanDEM data for forest height estimation and change detection

    Science.gov (United States)

    Thiele, Antje; Dubois, Clémence; Boldt, Markus; Hinz, Stefan

    2016-10-01

    Mapping of forest coverage and forest changes became an increasing issue due to deforestation and forest degradation. Moreover, the estimation of related indicators such as carbon reduction, biomass and wood capacity is of large interest for industry and politics. As forest height is an important contributing parameter for these indicators, the region-wide estimation of forest heights is an essential step. This article investigates the accuracy potential of forest height estimation that can be reached by the current configuration of the two SAR satellites TerraSAR-X and TanDEM-X. Depending on the chosen acquisition mode and flight geometry, products of different quality can be achieved. Eight InSAR data sets showing different characteristics in geometric resolution, length of baseline, and mapping time, are processed and analyzed. To enable a thorough evaluation of the estimated heights, first-pulse LIDAR point clouds and aerial ortho-images are used as reference data.

  3. A coupled DEM-DFN approach to rock mass strength characterization

    Science.gov (United States)

    Harthong, Barthelemy; Scholtes, Luc; Donze, Frederic

    2013-04-01

    An enhanced version of the discrete element method (DEM) has been specifically developed for the analysis of fractured rock masses [Scholtes L, Donze F, 2012]. In addition to the discrete representation of the intact medium which enables the description of the localized stress-induced damage caused by heterogeneities inherent to rocks, structural defects can be explicitly taken into account in the modeling to represent pre-existing fractures or discontinuities of size typically larger than the discrete element size. From laboratory scale simulations to slope stability case studies, the capability of this approach to simulate the progressive failure mechanisms occurring in jointed rock are presented is assessed on the basis of referenced experiments and in situ observations. For instance, the challenging wing crack extension, typical of brittle material fracturing, can be successfully reproduced under both compressive and shear loading path, as a result of the progressive coalescence of micro-cracks induced by stress concentration at the tips of pre-existing fractures. In this study, the dedicated DEM is coupled to a discrete fracture network (DFN) model to assess the influence of DFN properties on the mechanical behavior of fractured rock masses where progressive failure can occur. The DFN model assumes the distribution of fractures barycentres to be fractal and the distribution of fracture sizes to follow a power-law distribution [Davy P, Le Goc P, Darcel C, Bour O, de Dreuzy JR, Munier R, 2010]. The proposed DEM/DFN model is used to characterize the influence of clustering and size distribution of pre-existing fractures on the strength of fractured rock masses. The results show that the mechanical behaviour of fractured rock masses is mainly dependent on the fracture intensity. However, for a given fracture intensity, the strength can exhibit a 50 per cent variability depending on the size distribution of the pre-existing fractures. This difference can be

  4. DEM-CFD simulation of purge gas flow in a solid breeder pebble bed

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230027 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Zhenghong [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); University of Science and Technology of China, Hefei 230027 (China); Guo, Haibing [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Ye, Minyou [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230027 (China); Huang, Hongwen, E-mail: inpclane@sina.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-12-15

    Solid tritium breeding blanket applying pebble bed concept is promising for fusion reactors. Tritium bred in the pebble bed is purged out by inert gas. The flow characteristics of the purge gas are important for the tritium transport from the solid breeder materials. In this study, a randomly packed pebble bed was generated by Discrete Element Method (DEM) and verified by radial porosity distribution. The flow parameters of the purge gas in channels were solved by Computational Fluid Dynamics (CFD) method. The results show that the normalized velocity magnitudes have the same damped oscillating patterns with radial porosity distribution. Besides, the bypass flow near the wall cannot be ignored in this model, and it has a slight increase with inlet velocity. Furthermore, higher purging efficiency becomes with higher inlet velocity and especially higher in near wall region.

  5. Prevalência da polifarmácia em idosos com demência

    OpenAIRE

    Kusano, Liana Tieko Evangelista

    2009-01-01

    A polifarmácia entre os idosos tornou-se uma prática comum. A polifarmácia pode ser classificada como quantitativa e qualitativa. Dentre os conceitos para a quantitativa, definiu-se a mesma como sendo a utilização de dois ou mais medicamentos. Por sua vez, a polifarmácia qualitativa leva em consideração a racionalização da terapia farmacológica. A partir dos dois conceitos apresentados, este estudo objetivou avaliar a prevalência da polifarmácia nos idosos com demência e associa-las às caract...

  6. Quantenphysik und Kommunikationswissenschaft auf dem Weg zu einer allgemeinen Theorie der Kommunikation

    CERN Document Server

    Hamberger, Erich

    2015-01-01

    Der Quantenphysiker Herbert Pietschmann beschäftigt sich seit Jahrzehnten mit dem Phänomen Kommunikation. Der Kommunikationswissenschaftler Erich Hamberger setzt sich seit langem mit der Frage der Adaptierung erkenntnistheoretischer Einsichten der Quantentheorie für die Geistes- und Biowissenschaften auseinander. 2003 begegnen sich die beiden - und staunen über die „verschränkten Erkenntnisinteressen“. 2006 bestreiten sie eine erste gemeinsame universitäre Lehrveranstaltung. 2011 folgt Das Phänomen Kommunikation transdisziplinär betrachtet. Aus ihrer Zusammenarbeit ist dieses Buch entstanden. Naturwissenschaft arbeitet auf der Grundlage des mechanistischen Denkrahmens. Die bisher einzige Ausnahme ist die Quantenphysik. Weder Leben noch Kommunikation ist mittels des mechanistischen Denkrahmens zu verstehen. Auch der Denkrahmen der Quantenphysik reicht dazu nicht aus. Der Bedarf nach adäquatem Denken im Bereich der Kommunikation kann durch quantenphysikalisches Denken NICHT befriedigt werden, jedoc...

  7. Cerebellar volume in patients with dementia Volume cerebelar em pacientes com demência

    Directory of Open Access Journals (Sweden)

    Leonardo Baldaçara

    2011-06-01

    Mental e do Questionário de Atividades Funcionais. Os sujeitos foram divididos em cinco grupos de acordo com a Escala de Gravidade da Demência. Vinte e seis indivíduos do grupo original que não tinham o diagnóstico de demência no início do estudo foram reavaliados após dois anos para detectar o desenvolvimento da doença. RESULTADOS: Os volumes dos hemisférios cerebelares, lobo cerebelar posterior, vermis e lobo temporal estavam diminuídos proporcionalmente à gravidade da doença. Houve correlações positivas e significativas entre o Questionário de Atividades Funcionais, Mini Exame do Estado Mental e seus respectivos subtestes para linguagem e atenção com os volumes dos lobos temporal e cerebelar. A análise de regressão logística demonstrou que o volume reduzido do lobo temporal, lobo cerebelar posterior e vermis pode ser um fator de risco para o futuro desenvolvimento de demência. CONCLUSÃO: Este é o primeiro estudo que demonstrou que o volume do cerebelo pode estar reduzido na fase pré-demência e reforça o papel dessa estrutura na progressão da doença de Alzheimer. Considerando que o cerebelo pode não estar diretamente associado com a origem da doença de Alzheimer, este achado tem valor para o prognóstico.

  8. Cerebellar volume in patients with dementia Volume cerebelar em pacientes com demência

    Directory of Open Access Journals (Sweden)

    Leonardo Baldaçara

    2011-01-01

    Mental e do Questionário de Atividades Funcionais. Os sujeitos foram divididos em cinco grupos de acordo com a Escala de Gravidade da Demência. Vinte e seis indivíduos do grupo original que não tinham o diagnóstico de demência no início do estudo foram reavaliados após dois anos para detectar o desenvolvimento da doença. RESULTADOS: Os volumes dos hemisférios cerebelares, lobo cerebelar posterior, vermis e lobo temporal estavam diminuídos proporcionalmente à gravidade da doença. Houve correlações positivas e significativas entre o Questionário de Atividades Funcionais, Mini Exame do Estado Mental e seus respectivos subtestes para linguagem e atenção com os volumes do lobo temporal e cerebelar. A análise de regressão logística demonstrou que o volume reduzido do lobo temporal, lobo cerebelar posterior e vermis pode ser um fator de risco para o futuro desenvolvimento de demência. CONCLUSÃO: Este é o primeiro estudo que demonstrou que o volume do cerebelo pode estar reduzido na fase pré-demência e reforça o papel dessa estrutura na progressão da doença de Alzheimer. Considerando que o cerebelo pode não estar diretamente associado com a origem da doença de Alzheimer, este achado tem valor para o prognóstico.

  9. Atividade física, funções cognitivas e demência

    OpenAIRE

    Vaz, Filipe Malva Simões

    2014-01-01

    Introdução: O conceito de demência define uma deterioração adquirida na capacidade cognitiva que vai prejudicar o desempenho das atividades quotidianas. Sendo um processo que a nível epidemiológico tem a sua maior prevalência em doentes com mais de 85 anos, este é um pormenor de relevância social devido ao facto da projeção do número de idosos estar a crescer exponencialmente e da esperança média de vida continuar a aumentar. Neste quadro, verifica-se que o número de pessoas co...

  10. Coupled DEM-CFD analyses of landslide-induced debris flows

    CERN Document Server

    Zhao, Tao

    2017-01-01

    This book reflects the latest research results in computer modelling of landslide-induced debris flows. The book establishes an understanding of the initiation and propagation mechanisms of landslides by means of numerical simulations, so that mitigation strategies to reduce the long-term losses from landslide hazards can be devised. In this context, the book employs the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) to investigate the mechanical and hydraulic behaviour of granular materials involved in landslides – an approach that yields meaningful insights into the flow mechanisms, concerning e.g. the mobilization of sediments, the generation and dissipation of excess pore water pressures, and the evolution of effective stresses. As such, the book provides valuable information, useful methods and robust numerical tools that can be successfully applied in the field of debris flow research.

  11. DEM4-26, Least Square Fit for IBM PC by Deming Method

    International Nuclear Information System (INIS)

    Rinard, P.M.; Bosler, G.E.

    1989-01-01

    1 - Description of program or function: DEM4-26 is a generalized least square fitting program based on Deming's method. Functions built into the program for fitting include linear, quadratic, cubic, power, Howard's, exponential, and Gaussian; others can easily be added. The program has the following capabilities: (1) entry, editing, and saving of data; (2) fitting of any of the built-in functions or of a user-supplied function; (3) plotting the data and fitted function on the display screen, with error limits if requested, and with the option of copying the plot to the printer; (4) interpolation of x or y values from the fitted curve with error estimates based on error limits selected by the user; and (5) plotting the residuals between the y data values and the fitted curve, with the option copying the plot to the printer. 2 - Method of solution: Deming's method

  12. Robust 3D Quantification of Glacial Landforms: A Use of Idealised Drumlins in a Real DEM

    Science.gov (United States)

    Hillier, J. K.; Smith, M. S.

    2012-04-01

    Drumlins' attributes, such as height (h) and volume (V ), may preserve important information about the dynamics of former ice sheets. However, measurement errors are large (e.g., 39.2% of V within ±25% of their real values for the 'cookie cutter') and, in general, poorly understood. To accurately quantify the morphology of glacial landforms, the relief belonging to that landform must be reliably isolated from other components of the landscape (e.g. buildings, hills). A number of techniques have been proposed for this regional-residual separation (RRS). Which is best? Justifications for those applied remain qualitative assertions. A recently developed, novel method using idealised drumlins of known size (hin, V in) in a real digital elevation model (DEM) is used to quantitatively determine the best RRS technique, allowing general guidelines for quantifying glacial landforms to be proposed. 184 drumlins with digitised outlines in western Central Scotland are used as a case study. The NEXTMap surface model (DSM) is the primary dataset employed. A variety of techniques are then investigated for their ability to recover sizes (hr, V r). A metric, ɛ, is used that maximises the number of Hr/Hin values near 1.0 whilst giving equal weight to different drumlin sizes: a metric dominated by the large number of small drumlins is not desirable. For simplicity, the semi-automated 'cookie cutter' technique is used as a baseline for comparison. This removes heights within a drumlin from a DEM, cuts a hole, then estimates its basal surface by interpolating across the space with a fully tensioned bi-cubic spline (-T1). Metrics for h and V are ɛh = 0.885 and ɛV = 0.247. Other tensions do not improve this significantly, with ɛV of 0.245 at best, but using Delauney triangulation reduces ɛV to 0.206. Windowed 'sliding median' filters, which do not require heights within drumlins to be removed, attain a minimum ɛV of 0.470 at a best width of 340 m (-Fm340). Finally, even crudely

  13. Is the breakthrough of light electric-powered vehicles imminent?; Leicht-Elektromobile vor dem Durchbruch?

    Energy Technology Data Exchange (ETDEWEB)

    Stricker, B.

    1995-09-01

    Light electric-powered vehicles still exist in the shadow beside gasoline-operated automobiles. One reason for this lies in the economic recession, another in the marketing strategy for the Swatch vehicle due to be put on the market shortly. The report gives an overview of the light vehicles shown this year at Berne`s solar vehicle exhibition. TWIKE, an innovative, energy-efficient tricycle, is particularly pointed out. (BWI) [Deutsch] Leicht-Elektromobile fristen leider immer noch ein Schattendasein neben den benzinbetriebenen Automobilen. Der Grund dafuer ist neben der rezessiven Wirtschaftstendenz auch in der Marketing-Strategie fuer das zu erwartende Swatch-Mobil zu sehen. Der vorliegende Beitrag gibt einen Ueberblick ueber die auf dem diesjaehrigen Solarsalon in Bern gezeigten Leichtmobile. Besonders hervorgehoben wird dabei TWIKE, ein innovatives, energieeffizientes Dreirad. (BWI)

  14. Mechanistic Based DEM Simulation of Particle Attrition in a Jet Cup

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wei; DeCroix, David; Sun, Xin

    2014-02-01

    The attrition of particles is a major industrial concern in many fluidization systems as it can have undesired effects on the product quality and on the reliable operation of process equipment. Therefore, to accomodate the screening and selection of catalysts for a specific process in fluidized beds, risers, or cyclone applications, their attrition propensity is usually estimated through jet cup attrition testing, where the test material is subjected to high gas velocities in a jet cup. However, this method is far from perfect despite its popularity, largely due to its inconsistency in different testing set-ups. In order to better understand the jet cup testing results as well as their sensitivity to different operating conditions, a coupled computational fluid dynamic (CFD) - discrete element method (DEM) model has been developed in the current study to investigate the particle attrition in a jet cup and its dependence on various factors, e.g. jet velocity, initial particle size, particle density, and apparatus geometry.

  15. Comparison Between 2D and 3D Simulations of Rate Dependent Friction Using DEM

    Science.gov (United States)

    Wang, C.; Elsworth, D.

    2017-12-01

    Rate-state dependent constitutive laws of frictional evolution have been successful in representing many of the first- and second- order components of earthquake rupture. Although this constitutive law has been successfully applied in numerical models, difficulty remains in efficient implementation of this constitutive law in computationally-expensive granular mechanics simulations using discrete element methods (DEM). This study introduces a novel approach in implementing a rate-dependent constitutive relation of contact friction into DEM. This is essentially an implementation of a slip-weakening constitutive law onto local particle contacts without sacrificing computational efficiency. This implementation allows the analysis of slip stability of simulated fault gouge materials. Velocity-stepping experiments are reported on both uniform and textured distributions of quartz and talc as 3D analogs of gouge mixtures. Distinct local slip stability parameters (a-b) are assigned to the quartz and talc, respectively. We separately vary talc content from 0 to 100% in the uniform mixtures and talc layer thickness from 1 to 20 particles in the textured mixtures. Applied shear displacements are cycled through velocities of 1μm/s and 10μm/s. Frictional evolution data are collected and compared to 2D simulation results. We show that dimensionality significantly impacts the evolution of friction. 3D simulation results are more representative of laboratory observed behavior and numerical noise is shown at a magnitude of 0.01 in terms of friction coefficient. Stability parameters (a-b) can be straightforwardly obtained from analyzing velocity steps, and are different from locally assigned (a-b) values. Sensitivity studies on normal stress, shear velocity, particle size, local (a-b) values, and characteristic slip distance (Dc) show that the implementation is sensitive to local (a-b) values and relations between (Dc) and particle size.

  16. Quantitative Analysis of Accuracy of Voidage Computations in CFD-DEM Simulations

    Directory of Open Access Journals (Sweden)

    H. A. Khawaja

    2012-06-01

    Full Text Available CFD-DEM (Computational Fluid Dynamics – Discrete Element Modelling is a two-phase flow numerical modelling technique, where the Eulerian method is used for the fluid and the Lagrangian method for the particles. The two phases are coupled by a fluid-particle interaction force (i.e. drag force which is computed using a correlation. In a two-phase flow, one critical parameter is the voidage (or void fraction, which is defined as the ratio of the volume occupied by the fluid to the total volume. In a CFD-DEM simulation the local voidage is computed by calculating the volume of particles in a given fluid cell. For spherical particles, this computation is difficult when a particle is on the boundary of fluid cells. In this case, it is usual to compute the volume of a particle in a fluid cell approximately. One such approximation divides the volume of a particle into each cell in the same ratio as an equivalent cube of width equal to the particle diameter. Whilst this approach is computationally straight forward, the approximation introduces an error in the voidage computation. Here we estimate the error by comparing the approximate volume calculation with an exact (numerical computation of the volume of a particle in a fluid cell. The results show that the error varies with the position of the particle relative to the cell boundary. A new approach is suggested which limits the error to less than 2.5 %, without significantly increasing the computational complexity.

  17. Exploring the Potential of TanDEM-X Data in Rice Monitoring

    Science.gov (United States)

    Erten, E.

    2015-12-01

    In this work, phenological parameters such as growth stage, calendar estimation, crop density and yield estimation for rice fields are estimated employing TanDEM-X data. Currently, crop monitoring is country-dependent. Most countries have databases based on cadastral information and annual farmer inputs. Inaccuracies are coming from wrong or missing farmer declarations and/or coarsely updated cadastral boundary definitions. This leads to inefficient regulation of the market, frauds as well as to ecological risks. An accurate crop calendar is also missing, since farmers provide estimations in advance and there is no efficient way to know the growth status over large plantations. SAR data is of particular interest for these purposes. The proposed method includes two step approach including field detection and phenological state estimation. In the context of precise farming it is substantial to define field borders which are usually changing every cultivation period. Linking the SAR inherit properties to transplanting practice such as irrigation, the spatial database of rice-planted agricultural crops can be updated. Boundaries of agricultural fields will be defined in the database, and assignments of crops and sowing dates will be continuously updated by our monitoring system considering that sowing practice variously changes depending on the field owner decision. To define and segment rice crops, the system will make use of the fact that rice fields are characterized as flooded parcels separated by path networks composed by soil or rare grass. This natural segmentation is well detectable by inspecting low amplitude and coherence values of bistatic acquisitions. Once the field borders are defined, the phenology estimation of crops monitored at any time is the key point of monitoring. In this aspect the wavelength and the polarization option of TanDEM-X are enough to characterize the small phenological changes. The combination of bistatic interferometry and Radiative

  18. BOREAS HYP-8 DEM Data Over The NSA-MSA and SSA-MSA in The AEAC Projection

    Science.gov (United States)

    Knapp, David E.; Hall, Forrest G. (Editor); Wang, Xue-Wen; Band, L. E.; Smith, David E. (Technical Monitor)

    2000-01-01

    These data were derived from the original Digital Elevation Models (DEMs) produced by the Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-8 team. The original DEMs were in the Universal Transverse Mercator (UTM) projection, while this product is projected in the Albers Equal-Area Conic (AEAC) projection. The pixel size of the data is 100 meters, which is appropriate for the 1:50,000-scale contours from which the DEMs were made. The original data were compiled from information available in the 1970s and 1980s. This data set covers the two Modeling Sub-Areas (MSAs) that are contained within the Southern Study Area (SSA) and the Northern Study Area (NSA). The data are stored in binary, image format files. The DEM data over the NSA-MSA and SSA-MSA in the AEAC projection are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  19. Using high resolution DEMs to assess the effects of roads and trails on hydrological pathways that contribute to gully development

    Science.gov (United States)

    Sidle, R. C.; Jarihani, B.

    2017-12-01

    Dry savannas of northern Queensland, Australia experience severe gully erosion, particularly areas that have been heavily grazed. Field surveys have also noted the influence of unpaved roads and cattle trails on concentrating storm runoff into gully systems. To better quantify the effect of these roads and trails we use high resolution digital elevation models (DEMs) to develop indices of hydrological connectivity (IC) throughout drainage areas above and downstream of gully systems. High resolution (0.5m) DEMs from LiDAR were used to extract road and trail networks and drone-based very high resolution (0.1m) DEMs were used to extract cattle trials. IC is a function of the ratio of upslope to downslope sediment routing functions, which are based on upslope area, mean slope gradient, a weighting factor related to impedance to overland flow, and flow path distance (for the downstream function). Maps of IC within the heavily grazed Weany Creek catchment (13 km2) of northeast Queensland show that existing roads can increase hydrologic connectivity to gully systems. Furthermore, by adding roads and cattle trails into existing DEMs, we show how the extent and location of these curvilinear features affect overland flow concentration. Our findings can inform important hydrogeomorphic issues such as which gullies will likely headcut or expand and where new gullies may arise. Our analysis can also contribute to better management practices for grazing and road location.

  20. Validation of DEM Data Derived from World View 3 Stereo Imagery for Low Elevation Majuro Atoll, Marshall Islands

    Science.gov (United States)

    The availability of surface elevation data for the Marshall Islands has been identified as a “massive” data gap for conducting vulnerability assessments and the subsequent development of climate change adaption strategies. Specifically, digital elevation model (DEM) data are need...

  1. Comparison of SIFT and SURF based DEM extraction approaches on a GEOEYE-1 satellite stereo-pair

    Science.gov (United States)

    Daliakopoulos, Ioannis; Tsanis, Ioannis

    2014-05-01

    A MATLAB module for Digital Elevation Model (DEM) extraction from Very High Resolution (VHR) satellite stereo-pair imagery is used to compare the efficiency of two well established feature detection and description algorithms. A procedure for parallel processing of cascading image tiles is used for handling the large datasets requirements of VHR satellite imagery. Scale-Invariant Feature Transform (SIFT) and Speeded Up Robust Features (SURF) algorithms are used to detect potentially tentative feature matches in the members of the stereo-pair. The resulting feature pairs are filtered using the RANdom SAmple Consensus (RANSAC) algorithm by using a variable distance threshold. Finally, tentative feature matches are converted to point cloud ground coordinates for DEM generation. A 0.5 m × 0.5 m Geoeye-1 stereo-pair acquired over an area of 25 km2 in the island of Crete, Greece is used as input for the module. The resulting 2 m × 2 m DEMs has superior detail over previously developed 2 m and 5 m DEMs that are used as reference, and yields a Root Mean Square Error (RMSE) of about 1 m compared to ground truth measurements. Results suggest that SURF's superior runtime performance outweighs the slightly better feature quality attained with SIFT.

  2. DEM Development from Ground-Based LiDAR Data: A Method to Remove Non-Surface Objects

    Directory of Open Access Journals (Sweden)

    Maneesh Sharma

    2010-11-01

    Full Text Available Topography and land cover characteristics can have significant effects on infiltration, runoff, and erosion processes on watersheds. The ability to model the timing and routing of surface water and erosion is affected by the resolution of the digital elevation model (DEM. High resolution ground-based Light Detecting and Ranging (LiDAR technology can be used to collect detailed topographic and land cover characteristic data. In this study, a method was developed to remove vegetation from ground-based LiDAR data to create high resolution DEMs. Research was conducted on intensively studied rainfall–runoff plots on the USDA-ARS Walnut Gulch Experimental Watershed in Southeast Arizona. LiDAR data were used to generate 1 cm resolution digital surface models (DSM for 5 plots. DSMs created directly from LiDAR data contain non-surface objects such as vegetation cover. A vegetation removal method was developed which used a slope threshold and a focal mean filter method to remove vegetation and create bare earth DEMs. The method was validated on a synthetic plot, where rocks and vegetation were added incrementally. Results of the validation showed a vertical error of ±7.5 mm in the final DEM.

  3. Interkulturelle kommunikative Kompetenz – ein Versuch der Operationalisierung aus dem Fach Deutsch an der dänischen Lehrerausbildung

    DEFF Research Database (Denmark)

    Bjerre, Kirsten; Daryai-Hansen, Petra

    2017-01-01

    hierbei stellen. Im Anschluss präsentieren wir unser Modell der interkulturellen kommunikativen Kompetenz, das wir für das Fach Deutsch ain der dänischen Lehrerausbildung auf der Grundlage eines Modells von Michael Byram aus dem Jahre 1997 entwickelt haben. Byrams Modell der interkulturellen...

  4. Briefe aus dem Morgenland - Otto Friedrich von Richters Forschungsreise in den Jahren 1814-1816 / Vladimir Sazonov

    Index Scriptorium Estoniae

    Sazonov, Vladimir, 1979-

    2013-01-01

    Arvustus: Briefe aus dem Morgenland - Otto Friedrich von Richters Forschungsreise in den Jahren 1814-1816, hrsg. von Indrek Jürjo, Sergei Stadnikov, Hamburger Beiträge zur Geschichte des östlichen Europa, Bd. 20. Hamburg: Verlag Dr. Kovač 2013, 313 lk.

  5. Capturing Micro-topography of an Arctic Tundra Landscape through Digital Elevation Models (DEMs) Acquired from Various Remote Sensing Platforms

    Science.gov (United States)

    Vargas, S. A., Jr.; Tweedie, C. E.; Oberbauer, S. F.

    2013-12-01

    The need to improve the spatial and temporal scaling and extrapolation of plot level measurements of ecosystem structure and function to the landscape level has been identified as a persistent research challenge in the arctic terrestrial sciences. Although there has been a range of advances in remote sensing capabilities on satellite, fixed wing, helicopter and unmanned aerial vehicle platforms over the past decade, these present costly, logistically challenging (especially in the Arctic), technically demanding solutions for applications in an arctic environment. Here, we present a relatively low cost alternative to these platforms that uses kite aerial photography (KAP). Specifically, we demonstrate how digital elevation models (DEMs) were derived from this system for a coastal arctic landscape near Barrow, Alaska. DEMs of this area acquired from other remote sensing platforms such as Terrestrial Laser Scanning (TLS), Airborne Laser Scanning, and satellite imagery were also used in this study to determine accuracy and validity of results. DEMs interpolated using the KAP system were comparable to DEMs derived from the other platforms. For remotely sensing acre to kilometer square areas of interest, KAP has proven to be a low cost solution from which derived products that interface ground and satellite platforms can be developed by users with access to low-tech solutions and a limited knowledge of remote sensing.

  6. Investigation of Drag Force on Fibres of Bonded Spherical Elements using a Coupled CFD-DEM Approach

    DEFF Research Database (Denmark)

    Jensen, Anna Lyhne; Sørensen, Henrik; Rosendahl, Lasse Aistrup

    2016-01-01

    Clogging in wastewater pumps is often caused by flexible, stringy objects. Therefore, simulation of clogging effects in wastewater pumps entails simulation of such flexible objects and the interaction between these objects and fluid in the pump. Using a coupled CFD-DEM approach, the flexible obje...

  7. Assessment of neuro-optometric rehabilitation using the Developmental Eye Movement (DEM test in adults with acquired brain injury

    Directory of Open Access Journals (Sweden)

    Neera Kapoor

    2018-04-01

    Full Text Available Purpose: This pilot study sought to determine the efficacy of using the Developmental Eye Movement (DEM test in the adult, acquired brain injury (ABI population to quantify clinically the effects of controlled, laboratory-performed, oculomotor-based vision therapy/vision rehabilitation. Methods: Nine adult subjects with mild traumatic brain injury (mTBI and five with stroke were assessed before and after an eight-week, computer-based, versional oculomotor (fixation, saccades, pursuit, and simulated reading training program (9.6 h total. The protocol incorporated a cross-over, interventional design with and without the addition of auditory feedback regarding two-dimensional eye position. The clinical outcome measure was the Developmental Eye Movement (DEM test score (ratio, errors taken before, midway, and immediately following training. Results: For the DEM ratio parameter, improvements were found in 80–89% of the subjects. For the DEM error parameter, improvements were found in 100% of the subjects. Incorporation of the auditory feedback component revealed a trend toward enhanced performance. The findings were similar for both DEM parameters, as well as for incorporation of the auditory feedback, in both diagnostic groups. Discussion: The results of the present study demonstrated considerable improvements in the DEM test scores following the oculomotor-based training, thus reflecting more time-optimal and accurate saccadic tracking after the training. The DEM test should be considered as another clinical test of global saccadic tracking performance in the ABI population. Resumen: Objetivo: Este estudio piloto trató de determinar la eficacia del uso de la prueba DEM (Developmental Eye Movement en la población adulta con daño cerebral adquirido (DCA para cuantificar clínicamente los efectos de la rehabilitación/terapia visual controlada, realizada en laboratorio, y de carácter oculomotor. Métodos: Se valoraron nueve sujetos adultos con

  8. Sensitivity of a Floodplain Hydrodynamic Model to Satellite-Based DEM Scale and Accuracy: Case Study—The Atchafalaya Basin

    Directory of Open Access Journals (Sweden)

    Hahn Chul Jung

    2015-06-01

    Full Text Available The hydrodynamics of low-lying riverine floodplains and wetlands play a critical role in hydrology and ecosystem processes. Because small topographic features affect floodplain storage and flow velocity, a hydrodynamic model setup of these regions imposes more stringent requirements on the input Digital Elevation Model (DEM compared to upland regions with comparatively high slopes. This current study provides a systematic approach to evaluate the required relative vertical accuracy and spatial resolution of current and future satellite-based altimeters within the context of DEM requirements for 2-D floodplain hydrodynamic models. A case study is presented for the Atchafalaya Basin with a model domain of 1190 km2. The approach analyzes the sensitivity of modeled floodplain water elevation and velocity to typical satellite-based DEM grid-box scale and vertical error, using a previously calibrated version of the physically-based flood inundation model (LISFLOOD-ACC. Results indicate a trade-off relationship between DEM relative vertical error and grid-box size. Higher resolution models are the most sensitive to vertical accuracy, but the impact diminishes at coarser resolutions because of spatial averaging. The results provide guidance to engineers and scientists when defining the observation scales of future altimetry missions such as the   Surface Water and Ocean Topography (SWOT mission from the perspective of numerical modeling requirements for large floodplains of O[103] km2 and greater.

  9. Quality of topographic data from interferometry SAR DEM for hydrological researches: The case study of the Lesse and the Dendre rivers, Belgium

    Science.gov (United States)

    Shimoni, Michal; Moermans, Benoit; Hanquet, Bernard; Dautrebande, Sylvia

    2002-01-01

    For hydrology and terrestrial ecosystem studies, topography has a significant influence on the amount of intercepted solar radiation, the surface and sub-surface water movements, the type and distribution of vegetation and the microclimate. Processing Digital Elevation Model (DEM) data to extract hydrological features becomes a routine, but the numerous DEMs available stress the importance of their quality assessment. Radar interferometry (InSAR) technique is a promising approach to generate digital elevation models. The goal of this research is to verify to what extend the InSAR DEM can be used as a topographic database for deriving hydrological informations. This study was realised over the Dendre and the Lesse watersheds. Because DEM quality cannot be determined by a single criterion, the quality assessment should be application oriented. In this study, the NGI (National Geographic Institute of Belgium) DEM was chosen as a topographic reference for the quality assessment of the InSAR DEMs. The Root Mean Square (RMS) of the altitude difference between the NGI and the InSAR DEM was used as general quality measurement. The mean slope value has been calculated to characterise the relief of the basin. For both of the basins, watershed borders and hydrographic network were generated with GIS technique. The results obtained were compared between them and with digitised hydrographic network. Hydrographic network derived from InSAR DEM was not found accurate enough in flat wide valley. For the studied areas, the InSAR DEMs are precise enough for large-scale hydrological investigation where information like watershed border or relief is needed. However, InSAR DEMs is not suitable for hydraulic models, because they require extreme accuracy.

  10. Characterization of active fault scarps from medium to high resolution DEM: case studies from Central and Southern Apennines (Italy)

    Science.gov (United States)

    Brunori, C.; Cinti, F. R.; Ventura, G.

    2013-12-01

    We identify geo-morphometric features of active fault scarps in Italy through a semiautomatic processing using GIS. Medium to high resolution DEM was used to characterize the geometry, structural, and erosive elements of two seismogenic normal faults in Central and Southern Apennines. The Pettino fault in L'Aquila area was detected using a 1 m pixel DEM derived from airborne LiDAR survey (Friuli Venezia Giulia Civil Protection). For the Castrovillari fault in northern Calabria region was used a 4 m pixel DEM (Regional Cartography Office of Regione Calabria). Scarp segments are region of planar discontinuities identified by selected values of DEM-derived Terrain Ruggedness Index (TRI) and Vector Ruggedness Measure (VRM). These planar discontinuities corresponds to landscape features such as, river terraces, roads scarps, and other natural or human features. The discrimination between these features have been accomplished overlaying extracted features on aerial photograph, geological and geomorphologic maps and in situ survey. After that, we perform the quantitative and statistical analysis of these areas identified as "fault scarps". The identification of elements relative to the scarps (e.g. base, crest, slope) is then obtained to derive the estimate of parameters describing the fault: altitude, height of the scarp, length, slope and aspect, Terrain Ruggedness Index (TRI) and Vector Ruggedness Measure (VRM). The spatial distribution of the extracted values was obtained through their statistical analysis. We analyze scarp parameters variations along the whole scarp extent, such as strike value from aspect variations, slope and profile curvature differences as indicators of tectonic and/or erosion activity. The combined analysis of the DEM-derived parameters allows us to (a) define aspects of three-dimensional scarp geometry, (b) decipher its geomorphological significance, and (c) estimate the long-term slip rate.

  11. Anti-aliasing filters for deriving high-accuracy DEMs from TLS data: A case study from Freeport, Texas

    Science.gov (United States)

    Xiong, L.; Wang, G.; Wessel, P.

    2017-12-01

    Terrestrial laser scanning (TLS), also known as ground-based Light Detection and Ranging (LiDAR), has been frequently applied to build bare-earth digital elevation models (DEMs) for high-accuracy geomorphology studies. The point clouds acquired from TLS often achieve a spatial resolution at fingerprint (e.g., 3cm×3cm) to handprint (e.g., 10cm×10cm) level. A downsampling process has to be applied to decimate the massive point clouds and obtain portable DEMs. It is well known that downsampling can result in aliasing that causes different signal components to become indistinguishable when the signal is reconstructed from the datasets with a lower sampling rate. Conventional DEMs are mainly the results of upsampling of sparse elevation measurements from land surveying, satellite remote sensing, and aerial photography. As a consequence, the effects of aliasing have not been fully investigated in the open literature of DEMs. This study aims to investigate the spatial aliasing problem and implement an anti-aliasing procedure of regridding dense TLS data. The TLS data collected in the beach and dune area near Freeport, Texas in the summer of 2015 are used for this study. The core idea of the anti-aliasing procedure is to apply a low-pass spatial filter prior to conducting downsampling. This article describes the successful use of a fourth-order Butterworth low-pass spatial filter employed in the Generic Mapping Tools (GMT) software package as anti-aliasing filters. The filter can be applied as an isotropic filter with a single cutoff wavelength or as an anisotropic filter with different cutoff wavelengths in the X and Y directions. The cutoff wavelength for the isotropic filter is recommended to be three times the grid size of the target DEM.

  12. Digital Elevation Model (DEM), Countywide DEMs were created from the 2004 Maryland Statewide Lidar data.A map service has been created to host this data but local copies are recommended for complex processing and analysis as this data is very large.Contact the ESRGC to obtain a copy, Published in 2004, 1:1200 (1in=100ft) scale, Eastern Shore Regional GIS Cooperative.

    Data.gov (United States)

    NSGIC Regional | GIS Inventory — Digital Elevation Model (DEM) dataset current as of 2004. Countywide DEMs were created from the 2004 Maryland Statewide Lidar data.A map service has been created to...

  13. High-resolution DEM generation from multiple remote sensing data sources for improved volcanic hazard assessment - a case study from Nevado del Ruiz, Colombia

    Science.gov (United States)

    Deng, Fanghui; Dixon, Timothy H.; Rodgers, Mel; Charbonnier, Sylvain J.; Gallant, Elisabeth A.; Voss, Nicholas; Xie, Surui; Malservisi, Rocco; Ordoñez, Milton; López, Cristian M.

    2017-04-01

    Eruptions of active volcanoes in the presence of snow and ice can cause dangerous floods, avalanches and lahars, threatening millions of people living close to such volcanoes. Colombia's deadliest volcanic hazard in recorded history was caused by Nevado del Ruiz Volcano. On November 13, 1985, a relatively small eruption triggered enormous lahars, killing over 23,000 people in the city of Armero and 2,000 people in the town of Chinchina. Meltwater from a glacier capping the summit of the volcano was the main contributor to the lahars. From 2010 to present, increased seismicity, surface deformation, ash plumes and gas emissions have been observed at Nevado del Ruiz. The DEM is a key parameter for accurate prediction of the pathways of lava flows, pyroclastic flows, and lahars. While satellite coverage has greatly improved the quality of DEMs around the world, volcanoes remain a challenging target because of extremely rugged terrain with steep slopes and deeply cut valleys. In this study, three types of remote sensing data sources with different spatial scales (satellite radar interferometry, terrestrial radar interferometry (TRI), and structure from motion (SfM)) were combined to generate a high resolution DEM (10 m) of Nevado del Ruiz. 1) Synthetic aperture radar (SAR) images acquired by TSX/TDX satellites were applied to generate DEM covering most of the study area. To reduce the effect of geometric distortion inherited from SAR images, TSX/TDX DEMs from ascending and descending orbits were merged to generate a 10×10 m DEM. 2) TRI is a technique that uses a scanning radar to measure the amplitude and phase of a backscattered microwave signal. It provides a more flexible and reliable way to generate DEMs in steep-slope terrain compared with TSX/TDX satellites. The TRI was mounted at four different locations to image the upper slopes of the volcano. A DEM with 5×5 m resolution was generated by TRI. 3) SfM provides an alternative for shadow zones in both TSX/TDX and

  14. Fast 3D-EM reconstruction using Planograms for stationary planar positron emission mammography camera.

    Science.gov (United States)

    Motta, A; Guerra, A Del; Belcari, N; Moehrs, S; Panetta, D; Righi, S; Valentini, D

    2005-12-01

    At the University of Pisa we are building a PEM prototype, the YAP-PEM camera, consisting of two opposite 6 x 6 x 3 cm3 detector heads of 30 x 30 YAP:Ce finger crystals, 2 x 2 x 30 mm3 each. The camera will be equipped with breast compressors. The acquisition will be stationary. Compared with a whole body PET scanner, a planar Positron Emission Mammography (PEM) camera allows a better, easier and more flexible positioning around the breast in the vicinity of the tumor: this increases the sensitivity and solid angle coverage, and reduces cost. To avoid software rejection of data during the reconstruction, resulting in a reduced sensitivity, we adopted a 3D-EM reconstruction which uses all of the collected Lines Of Response (LORs). This skips the PSF distortion given by data rebinning procedures and/or Fourier methods. The traditional 3D-EM reconstruction requires several times the computation of the LOR-voxel correlation matrix, or probability matrix {p(ij)}; therefore is highly time-consuming. We use the sparse and symmetry properties of the matrix {p(ij)} to perform fast 3D-EM reconstruction. Geometrically, a 3D grid of cubic voxels (FOV) is crossed by several divergent 3D line sets (LORs). The symmetries occur when tracing different LORs produces the same p(ij) value. Parallel LORs of different sets cross the FOV in the same way, and the repetition of p(ij) values depends on the ratio between the tube and voxel sizes. By optimizing this ratio, the occurrence of symmetries is increased. We identify a nucleus of symmetry of LORs: for each set of symmetrical LORs we choose just one LOR to be put in the nucleus, while the others lie outside. All of the possible p(ij) values are obtainable by tracking only the LORs of this nucleus. The coordinates of the voxels of all of the other LORs are given by means of simple translation rules. Before making the reconstruction, we trace the LORs of the nucleus to find the intersecting voxels, whose p(ij) values are computed and

  15. Mechanized ultrasonic inspection of austenitic pipe systems; Mechanisierte Ultraschallpruefung von austenitischen Rohrleitungen

    Energy Technology Data Exchange (ETDEWEB)

    Dressler, K.; Luecking, J.; Medenbach, S. [ABB ZAQ GmbH, Essen (Germany)

    1999-08-01

    The contribution explains the system of standard testing methods elaborated by ABB ZAQ GmbH for inspection of austenitic plant components. The inspection tasks explained in greater detail are basic materials testing (straight pipes, bends, and pipe specials), and inspection of welds and dissimilar welds. The techniques discussed in detail are those for detection and sizing of defects. (orig./CB) [Deutsch] Das Ziel dieses Beitrages ist die Vorstellung der von der ABB ZAQ GmbH eingesetzten Standardprueftechniken fuer die Pruefung austenitischer Anlagenkomponenten. Im einzelnen wird die Grundwerkstoffpruefung (Rohre, Boegen, Formstuecke), die Schweissnahtpruefung und die Mischnahtpruefung angesprochen. Es werden dabei die Techniken fuer `Detection` und `Sizing` differenziert betrachtet und erlaeutert. (orig.)

  16. Hydrogen effects in nitrogen-alloyed austenitic steels; Wirkung von Wasserstoff in stickstofflegierten austenitischen Staehlen

    Energy Technology Data Exchange (ETDEWEB)

    Uhlemann, M.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Shehata, M.F. [National Research Centre, Cairo (Egypt)

    1998-12-31

    Hydrogen increases the yield strength of nitrogen-alloyed steels, but on the other hand adversely affects properties such as tensile strength and elongation to fracture. The effect is enhanced with increasing nitrogen and hydrogen contents. Under the effect of hydrogen addition, the discontinuous stress-strain characteristic and the distinct elongation limit of hydrogen-free, nitrogen containing steels is no longer observed in the material. This change of mechanical properties is attributed to an interatomic interaction of nitrogen and hydrogen in the lattice, which is shown for instance by such effects as reduction of hydrogen velocity, high solubility, and a particularly strong lattice expansion. The nature of this interaction of nitrogen and hydrogen in the fcc lattice remains to be identified. (orig./CB) [Deutsch] Wasserstoff fuehrt in stickstofflegierten Staehlen zu einer Erhoehung der Streckgrenze, aber gleichzeitig zu einer Abnahme der Zugfestigkeit und Bruchdehnung. Dieser Effekt verstaerkt sich mit zunehmenden Stickstoff- und Wasserstoffgehalten. Ein diskontinuierlicher Spannungs-Dehnungsverlauf mit einer ausgepraegten Streckgrenze in wasserstofffreien hochstickstoffhaltigen Staehlen wird nach Wasserstoffeinfluss nicht mehr beobachtet. Die Aenderung der mechanischen Eigenschaften, wird auf eine interatomare Wechselwirkung von Stickstoff und Wasserstoff im Gitter zurueckgefuehrt, die sich u.a. in geringer Wasserstoffdiffusionsgeschwindigkeit, hoher Loeslichkeit und vor allem in extremer Gitteraufweitung aeussert. Insgesamt ist die Natur der Wechselwirkung zwischen Stickstoff und Wasserstoff im kfz Gitter noch nicht aufgeklaert. (orig.)

  17. CREATION OF A MULTIRESOLUTION AND MULTIACCURACY DTM: PROBLEMS AND SOLUTIONS FOR HELI-DEM CASE STUDY

    Directory of Open Access Journals (Sweden)

    L. Biagi

    2014-01-01

    Full Text Available The work is part of "HELI-DEM" (HELvetia-Italy Digital Elevation Model project, funded by the European Regional Development Fund within the Italy-Switzerland cooperation program. The aim of the project is the creation of a unique DTM for the alpine and subalpine area between Italy (Piedmont, Lombardy and Switzerland (Ticino and Grisons Cantons; at present, different DTMs, that are in different reference frames and have been obtained with different technologies, accuracies, and resolutions, have been acquired. The final DTM should be correctly georeferenced and produced validating and integrating the data that are available for the project. DTMs are fundamental in hydrogeological studies, especially in alpine areas where hydrogeological risks may exist. Moreover, when an event, like for example a landslide, happens at the border between countries, a unique and integrated DTM which covers the interest area is useful to analyze the scenario. In this sense, HELI-DEM project is helpful. To perform analyses along the borders between countries, transnational geographic information is needed: a transnational DTM can be obtained by merging regional low resolution DTMs. Moreover high resolution local DTMs should be used where they are available. To be merged, low and high resolution DTMs should be in the same three dimensional reference frame, should not present biases and should be consistent in the overlapping areas. Cross-validation between the different DTMs is therefore needed. Two different problems should be solved: the merging of regional, partly overlapping low and medium resolution DTMs into a unique low/medium resolution DTM and the merging with other local high resolution/high accuracy height data. This paper discusses the preliminary processing of the data for the fusion of low and high resolution DTMs in a study-case area within the Lombardy region: Valtellina valley. In this region the Lombardy regional low resolution DTM is available, with

  18. Geomorphic Flood Area (GFA): a DEM-based tool for flood susceptibility mapping at large scales

    Science.gov (United States)

    Manfreda, S.; Samela, C.; Albano, R.; Sole, A.

    2017-12-01

    Flood hazard and risk mapping over large areas is a critical issue. Recently, many researchers are trying to achieve a global scale mapping encountering several difficulties, above all the lack of data and implementation costs. In data scarce environments, a preliminary and cost-effective floodplain delineation can be performed using geomorphic methods (e.g., Manfreda et al., 2014). We carried out several years of research on this topic, proposing a morphologic descriptor named Geomorphic Flood Index (GFI) (Samela et al., 2017) and developing a Digital Elevation Model (DEM)-based procedure able to identify flood susceptible areas. The procedure exhibited high accuracy in several test sites in Europe, United States and Africa (Manfreda et al., 2015; Samela et al., 2016, 2017) and has been recently implemented in a QGIS plugin named Geomorphic Flood Area (GFA) - tool. The tool allows to automatically compute the GFI, and turn it into a linear binary classifier capable of detecting flood-prone areas. To train this classifier, an inundation map derived using hydraulic models for a small portion of the basin is required (the minimum is 2% of the river basin's area). In this way, the GFA-tool allows to extend the classification of the flood-prone areas across the entire basin. We are also defining a simplified procedure for the estimation of the river depth, which may be helpful for large-scale analyses to approximatively evaluate the expected flood damages in the surrounding areas. ReferencesManfreda, S., Nardi, F., Samela, C., Grimaldi, S., Taramasso, A. C., Roth, G., & Sole, A. (2014). Investigation on the use of geomorphic approaches for the delineation of flood prone areas. J. Hydrol., 517, 863-876. Manfreda, S., Samela, C., Gioia, A., Consoli, G., Iacobellis, V., Giuzio, L., & Sole, A. (2016). Flood-prone areas assessment using linear binary classifiers based on flood maps obtained from 1D and 2D hydraulic models. Nat. Hazards, Vol. 79 (2), pp 735-754. Samela, C

  19. Understanding the microscopic moisture migration in pore space using DEM simulation

    Directory of Open Access Journals (Sweden)

    Yuan Guo

    2015-04-01

    Full Text Available The deformation of soil skeleton and migration of pore fluid are the major factors relevant to the triggering of and damages by liquefaction. The influence of pore fluid migration during earthquake has been demonstrated from recent model experiments and field case studies. Most of the current liquefaction assessment models are based on testing of isotropic liquefiable materials. However the recent New Zealand earthquake shows much severer damages than those predicted by existing models. A fundamental cause has been contributed to the embedded layers of low permeability silts. The existence of these silt layers inhibits water migration under seismic loads, which accelerated liquefaction and caused a much larger settlement than that predicted by existing theories. This study intends to understand the process of moisture migration in the pore space of sand using discrete element method (DEM simulation. Simulations were conducted on consolidated undrained triaxial testing of sand where a cylinder sample of sand was built and subjected to a constant confining pressure and axial loading. The porosity distribution was monitored during the axial loading process. The spatial distribution of porosity change was determined, which had a direct relationship with the distribution of excess pore water pressure. The non-uniform distribution of excess pore water pressure causes moisture migration. From this, the migration of pore water during the loading process can be estimated. The results of DEM simulation show a few important observations: (1 External forces are mainly carried and transmitted by the particle chains of the soil sample; (2 Porosity distribution during loading is not uniform due to non-homogeneous soil fabric (i.e. the initial particle arrangement and existence of particle chains; (3 Excess pore water pressure develops differently at different loading stages. At the early stage of loading, zones with a high initial porosity feature higher

  20. EXPERIMENTAL DEM EXTRACTION FROM ASTER STEREO PAIRS AND 3D REGISTRATION BASED ON ICESAT LASER ALTIMETRY DATA IN UPSTREAM AREA OF LAMBERT GLACIER, ANTARCTICA

    Directory of Open Access Journals (Sweden)

    G. Hai

    2017-09-01

    Full Text Available DEM Extraction from ASTER stereo pairs and three-dimensional registration by reference to ICESat laser altimetry data are carried out in upstream area of Lambert Glacier, East Antarctica. Since the study area is located in inland of East Antarctica where few textures exist, registration between DEM and ICESat data is performed. Firstly, the ASTER DEM generation is based on rational function model (RFM and the procedure includes: a rational polynomial coefficient (RPC computation from ASTER metadata, b L1A image product de-noise and destriping, c local histogram equalization and matching, d artificial collection of tie points and bundle adjustment, and e coarse-to-fine hierarchical matching of five levels and grid matching. The matching results are filtered semi-automatically. Hereafter, DEM is interpolated using spline method with ground points converted from matching points. Secondly, the generated ASTER DEM is registered to ICESat data in three-dimensional space after Least-squares rigid transformation using singular value decomposition (SVD. The process is stated as: a correspondence selection of terrain feature points from ICESat and DEM profiles, b rigid transformation of generated ASTER DEM using selected feature correspondences based on least squares technique. The registration shows a good result that the elevation difference between DEM and ICESat data is low with a mean value less than 2 meters and the standard deviation around 7 meters. This DEM is generated and specially registered in Antarctic typical region without obvious ground rock control points and serves as true terrain input for further radar altimetry simulation.

  1. Experimental dem Extraction from Aster Stereo Pairs and 3d Registration Based on Icesat Laser Altimetry Data in Upstream Area of Lambert Glacier, Antarctica

    Science.gov (United States)

    Hai, G.; Xie, H.; Chen, J.; Chen, L.; Li, R.; Tong, X.

    2017-09-01

    DEM Extraction from ASTER stereo pairs and three-dimensional registration by reference to ICESat laser altimetry data are carried out in upstream area of Lambert Glacier, East Antarctica. Since the study area is located in inland of East Antarctica where few textures exist, registration between DEM and ICESat data is performed. Firstly, the ASTER DEM generation is based on rational function model (RFM) and the procedure includes: a) rational polynomial coefficient (RPC) computation from ASTER metadata, b) L1A image product de-noise and destriping, c) local histogram equalization and matching, d) artificial collection of tie points and bundle adjustment, and e) coarse-to-fine hierarchical matching of five levels and grid matching. The matching results are filtered semi-automatically. Hereafter, DEM is interpolated using spline method with ground points converted from matching points. Secondly, the generated ASTER DEM is registered to ICESat data in three-dimensional space after Least-squares rigid transformation using singular value decomposition (SVD). The process is stated as: a) correspondence selection of terrain feature points from ICESat and DEM profiles, b) rigid transformation of generated ASTER DEM using selected feature correspondences based on least squares technique. The registration shows a good result that the elevation difference between DEM and ICESat data is low with a mean value less than 2 meters and the standard deviation around 7 meters. This DEM is generated and specially registered in Antarctic typical region without obvious ground rock control points and serves as true terrain input for further radar altimetry simulation.

  2. Insight From the Statistics of Nothing: Estimating Limits of Change Detection Using Inferred No-Change Areas in DEM Difference Maps and Application to Landslide Hazard Studies

    Science.gov (United States)

    Haneberg, W. C.

    2017-12-01

    Remote characterization of new landslides or areas of ongoing movement using differences in high resolution digital elevation models (DEMs) created through time, for example before and after major rains or earthquakes, is an attractive proposition. In the case of large catastrophic landslides, changes may be apparent enough that simple subtraction suffices. In other cases, statistical noise can obscure landslide signatures and place practical limits on detection. In ideal cases on land, GPS surveys of representative areas at the time of DEM creation can quantify the inherent errors. In less-than-ideal terrestrial cases and virtually all submarine cases, it may be impractical or impossible to independently estimate the DEM errors. Examining DEM difference statistics for areas reasonably inferred to have no change, however, can provide insight into the limits of detectability. Data from inferred no-change areas of airborne LiDAR DEM difference maps of the 2014 Oso, Washington landslide and landslide-prone colluvium slopes along the Ohio River valley in northern Kentucky, show that DEM difference maps can have non-zero mean and slope dependent error components consistent with published studies of DEM errors. Statistical thresholds derived from DEM difference error and slope data can help to distinguish between DEM differences that are likely real—and which may indicate landsliding—from those that are likely spurious or irrelevant. This presentation describes and compares two different approaches, one based upon a heuristic assumption about the proportion of the study area likely covered by new landslides and another based upon the amount of change necessary to ensure difference at a specified level of probability.

  3. BRS Deméter: nova cultivar de cevada cervejeira irrigada para o Cerrado do Brasil Central BRS Deméter: new malting barley cultivar for irrigated Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Renato Fernando Amabile

    2008-09-01

    Full Text Available BRS Deméter é uma cultivar de cevada dística (duas fileiras de grãos de ampla adaptação, sob irrigação, ao Cerrado do Brasil Central. Apresenta potencial produtivo de grãos acima de 5.000 kg ha-1, estabilidade de produção e alta qualidade industrial malte-cervejeira. A cultivar atende às demandas do produtor por rendimento competitivo e às da indústria malteira por alta qualidade cervejeira.BRS Deméter is a spring, two-rowed barley, widely adapted to irrigated areas of the savanna, in Central Brazil. It presents production stability and high malting quality, with yield potential above 5,000 kg ha-1. It fulfills both the farmer and malting industry expectations regarding competitive yield and brewing quality.

  4. Case studies of heat conduction in rotary drums with L-shaped lifters via DEM

    Directory of Open Access Journals (Sweden)

    Qiang Xie

    2018-03-01

    Full Text Available Rotary drums are widely used in numerous processes in industry to handle granular materials. In present work, heat transfer processes in drums with L-shaped lifters have been investigated by coupling the discrete element method (DEM with heat transfer model. Effects of both operational and structural parameters have been analyzed. It is found that increasing rotational speed could improve heat transfer to a certain extent, however, just in relatively low speed stage. When lifter number increases, the heat transfer speed slightly decreases. An increasing lifter height could promote heat transfer first and then reduces it, but the amplitude of variation keeps small. The heat transfer rate descends with increasing lifter width. The heat transfer mechanisms have also been discussed by comparing mixing rates, total contact areas for thermal conduction, time constants (TC indicating apparent heat transfer rate and effective heat transfer coefficients(HTC. It is concluded that dynamic conduction due to particle flow is dominated in all cases. The L-shaped lifers are turned out not a good choice when heat conduction between particles is prominent.

  5. CFD-DEM Analysis of Particle Attrition in a Jet in a Fluidised Bed

    Directory of Open Access Journals (Sweden)

    Fulchini F.

    2017-01-01

    Full Text Available In fluidised bed processes, the solids are in vigorous motion and thus inevitably subjected to mechanical stresses due to inter-particle and particle-wall impacts. These stresses lead to a gradual degradation of the particles by surface wear, abrasion and body fragmentation commonly termed attrition. One significant contribution of attrition comes from the air jets of the fluidised bed distributor. Particles are entrained into the air jet, where they get accelerated and impacted onto the fluidised bed particles. The jet induced attrition only affects the part of the bed which is limited by the jet length, where the mode of attrition is largely collisional. The overall jet attrition rate is therefore the result of the combination of the single particle damage and the flux of particles entering into that region. The attrition behaviour of particles in the jet region is analysed by evaluating their propensity of breakage experimentally and by simulating an air-jet in a bed of particles by CFD-DEM. The frequency of collisions and impact velocities are estimated from which the attrition due to a single air-jet is predicted.

  6. DEM simulations of shear flow of spherical particles mixed with long granular rods

    Science.gov (United States)

    Baran, Oleh

    2015-11-01

    Using Discrete Element Method (DEM) I investigate the effect of adding rigid rod-shape particles to the granular flow of spherical particles inside ring shear tester. The simulated geometry includes an annulus, bounded by two concentric cylindrical walls rested on a stationary bottom disk and covered with a top lid. Both the top lid and the bottom have protruding vanes oriented radially and uniformly spaced around the annulus, to prevent slipping of the bulk solid, see image at this link. The top lid rotates with a controlled angular speed and applies a constant normal load to the tested material. I analyze the results for shear stress on the top lid as a function of time for the mixture of spheres and rods and compare these results with ones obtained for the same amount of spherical particles without rods. I also present the analysis of the orientation of granular rods in a shear flow and discuss the results in terms of new time-scale related to the mobility of rods.

  7. DEM simulation of flow of dumbbells on a rough inclined plane

    Science.gov (United States)

    Mandal, Sandip; Khakhar, Devang

    2015-11-01

    The rheology of non-spherical granular materials such as food grains, sugar cubes, sand, pharmaceutical pills, among others, is not understood well. We study the flow of non-spherical dumbbells of different aspect ratios on a rough inclined plane by using soft sphere DEM simulations. The dumbbells are generated by fusing two spheres together and a linear spring dashpot model along with Coulombic friction is employed to calculate inter-particle forces. At steady state, a uni-directional shear flow is obtained which allows for a detailed study of the rheology. The effect of aspect ratio and inclination angle on mean velocity, volume fraction, shear rate, shear stress, pressure and viscosity profiles is examined. The effect of aspect ratio on probability distribution of angles, made by the major axes of the dumbbells with the flow direction, average angle and order parameter is analyzed. The dense flow rheology is well explained by Bagnold's law and the constitutive laws of JFP model. The dependencies of first and second normal stress differences on aspect ratio are studied. The probability distributions of translational and rotational velocity are analyzed.

  8. Modelling of Coke Layer Collapse during Ore Charging in Ironmaking Blast Furnace by DEM

    Science.gov (United States)

    Narita, Yoichi; Mio, Hiroshi; Orimoto, Takashi; Nomura, Seiji

    2017-06-01

    A technical issue in an ironmaking blast furnace operation is to realize the optimum layer thickness and the radial distribution of burden (ore and coke) to enhance its efficiency and productivity. When ore particles are charged onto the already-embedded coke layer, the coke layer-collapse phenomenon occurs. The coke layer-collapse phenomenon has a significant effect on the distribution of ore and coke layer thickness in the radial direction. In this paper, the mechanical properties of coke packed bed under ore charging were investigated by the impact-loading test and the large-scale direct shear test. Experimental results show that the coke particle is broken by the impact force of ore charging, and the particle breakage leads to weaken of coke-layer strength. The expression of contact force for coke in Discrete Element Method (DEM) was modified based on the measured data, and it followed by the 1/3-scaled experiment on coke's collapse phenomena. Comparing a simulation by modified model to the 1/3-scaled experiment, they agreed well in the burden distribution.

  9. CFD-DEM Analysis of Particle Attrition in a Jet in a Fluidised Bed

    Science.gov (United States)

    Fulchini, F.; Nan, W.; Ghadiri, M.; Yazdan Panah, M.; Bertholin, S.; Amblard, B.; Cloupet, A.; Gauthier, T.

    2017-06-01

    In fluidised bed processes, the solids are in vigorous motion and thus inevitably subjected to mechanical stresses due to inter-particle and particle-wall impacts. These stresses lead to a gradual degradation of the particles by surface wear, abrasion and body fragmentation commonly termed attrition. One significant contribution of attrition comes from the air jets of the fluidised bed distributor. Particles are entrained into the air jet, where they get accelerated and impacted onto the fluidised bed particles. The jet induced attrition only affects the part of the bed which is limited by the jet length, where the mode of attrition is largely collisional. The overall jet attrition rate is therefore the result of the combination of the single particle damage and the flux of particles entering into that region. The attrition behaviour of particles in the jet region is analysed by evaluating their propensity of breakage experimentally and by simulating an air-jet in a bed of particles by CFD-DEM. The frequency of collisions and impact velocities are estimated from which the attrition due to a single air-jet is predicted.

  10. DNS-DEM of Suspended Sediment Particles in an Open Channel Flow

    Science.gov (United States)

    Pakseresht, Pedram; Apte, Sourabh; Finn, Justin

    2016-11-01

    DNS with point-particle based discrete element model (DEM) is used to study particle-turbulence interactions in an open channel flow at Reτ of 710, corresponding to the experimental observations of Righetti & Romano. Large particles of diameter 200 microns (10 in wall units) with volume loading on the order of 10-3 are simulated using four-way coupling with closure models for drag, added mass, lift, pressure, and inter-particle collision forces. The point-particle model is able to accurately capture the effect of particles on the fluid flow in the outer layer. However, the particle is significantly larger than the wall-normal grid in the near-wall region, but slightly smaller than the axial and longitudinal grid resolutions. The point-particle model fails to capture the interactions in the near-wall region. In order to improve the near-wall predictions, particles are represented by Lagrangian material points which are used to perform interpolations from the grid to the Lagrangian points and to distribute the two-way coupling force to the Eulerian grid. Predictions using this approach is compared with the experimental data to evaluate its effectiveness. NSF project #1133363, Sediment-Bed-Turbulence Coupling in Oscillatory Flows.

  11. Numerical modelling by the Stokes--DEM coupled simulation for a roof at hot magma chamber

    Science.gov (United States)

    Furuichi, M.; Nishiura, D.

    2014-12-01

    The dynamics of a granular media has been suggested to play an important role in a reheated magma chamber by a hot intrusion (e.g. Burgisser and Bergantz, 2011). Although several mechanisms, such as Rayleigh Taylor instability, unzipping, and rhythmic convection (e.g. Shibano et.al. 2012, 2013), have been proposed for characterizing upward migration process in a crystalline magma chamber, their contributions in the long geodynamical time scale are not clear yet. Thus we perform numerical simulations to investigate the thermal evolution of the magma chamber with basal intrusion in three dimensions. In order to solve high-viscosity fluid and particle dynamics for modelling a melt--crystal jammed state of the magma, we have developed a coupled Stokes--DEM simulation code with two key techniques: formulation of particle motion without inertia and semi-implicit treatment of particle motion in the fluid equation (Furuichi and Nishiura 2014). Our simulation can successfully handle sinking particles in a high-viscosity fluid. We examine different types of the granular media heated from the bottom with varying parameters. We especially focus on pattern of the settling particles against the melt density contrast between upper and lower region.

  12. Modelling of Coke Layer Collapse during Ore Charging in Ironmaking Blast Furnace by DEM

    Directory of Open Access Journals (Sweden)

    Narita Yoichi

    2017-01-01

    Full Text Available A technical issue in an ironmaking blast furnace operation is to realize the optimum layer thickness and the radial distribution of burden (ore and coke to enhance its efficiency and productivity. When ore particles are charged onto the already-embedded coke layer, the coke layer-collapse phenomenon occurs. The coke layer-collapse phenomenon has a significant effect on the distribution of ore and coke layer thickness in the radial direction. In this paper, the mechanical properties of coke packed bed under ore charging were investigated by the impact-loading test and the large-scale direct shear test. Experimental results show that the coke particle is broken by the impact force of ore charging, and the particle breakage leads to weaken of coke-layer strength. The expression of contact force for coke in Discrete Element Method (DEM was modified based on the measured data, and it followed by the 1/3-scaled experiment on coke’s collapse phenomena. Comparing a simulation by modified model to the 1/3-scaled experiment, they agreed well in the burden distribution.

  13. DEM simulation of dendritic grain random packing: application to metal alloy solidification

    Science.gov (United States)

    Olmedilla, Antonio; Založnik, Miha; Combeau, Hervé

    2017-06-01

    The random packing of equiaxed dendritic grains in metal-alloy solidification is numerically simulated and validated via an experimental model. This phenomenon is characterized by a driving force which is induced by the solid-liquid density difference. Thereby, the solid dendritic grains, nucleated in the melt, sediment and pack with a relatively low inertia-to-dissipation ratio, which is the so-called Stokes number. The characteristics of the particle packed porous structure such as solid packing fraction affect the final solidified product. A multi-sphere clumping Discrete Element Method (DEM) approach is employed to predict the solid packing fraction as function of the grain geometry under the solidification conditions. Five different monodisperse noncohesive frictionless particle collections are numerically packed by means of a vertical acceleration: a) three dendritic morphologies; b) spheres and c) one ellipsoidal geometry. In order to validate our numerical results with solidification conditions, the sedimentation and packing of two monodisperse collections (spherical and dendritic) is experimentally carried out in a viscous quiescent medium. The hydrodynamic similarity is respected between the actual phenomenon and the experimental model, that is a low Stokes number, o(10-3). In this way, the experimental average solid packing fraction is employed to validate the numerical model. Eventually, the average packing fraction is found to highly depend on the equiaxed dendritic grain sphericity, with looser packings for lower sphericity.

  14. Blurring the boundary between rapid granular flow and dense granular flow regimes: Evidence from DEM simulations

    Science.gov (United States)

    Tripathi, Anurag; Prasad, Mahesh; Kumar, Puneet

    2017-11-01

    The saturation of the effective friction coefficient for granular flows at high inertial numbers has been assumed widely by researchers, despite little simulation/experimental evidence. In contrast, a recent simulation study of plane shear flows by Mandal and Khakhar, suggests that the effective friction coefficient becomes maximum and then starts to decrease with increase in the inertial number for I > 0.5 . In order to investigate whether such a dip at higher inertial numbers is indeed a feature of granular rheology, we perform DEM simulations of chute flow of highly inelastic disks. We show that steady, fully developed flows are possible at inclinations much higher than those normally reported in literature. At such high inclinations, the flow is characterised by a significant slip at the base; the height of the layer increases by more than 300 % and kinetic energy of the layer increases by nearly 5 orders of magnitude. We observe, for the first time, steady chute flows at inertial number I 2 and show that the dip at higher inertial numbers can be observed in case of chute flow as well. The predictions of modified μ - I rheology, however, seem to remain valid in the bulk of the layer for packing fractions as low as 0.2. AT acknowledges the funding obtained from IIT Kanpur through the initiation Grant for this study.

  15. Automated Topographic Change Detection via Dem Differencing at Large Scales Using The Arcticdem Database

    Science.gov (United States)

    Candela, S. G.; Howat, I.; Noh, M. J.; Porter, C. C.; Morin, P. J.

    2016-12-01

    In the last decade, high resolution satellite imagery has become an increasingly accessible tool for geoscientists to quantify changes in the Arctic land surface due to geophysical, ecological and anthropomorphic processes. However, the trade off between spatial coverage and spatial-temporal resolution has limited detailed, process-level change detection over large (i.e. continental) scales. The ArcticDEM project utilized over 300,000 Worldview image pairs to produce a nearly 100% coverage elevation model (above 60°N) offering the first polar, high spatial - high resolution (2-8m by region) dataset, often with multiple repeats in areas of particular interest to geo-scientists. A dataset of this size (nearly 250 TB) offers endless new avenues of scientific inquiry, but quickly becomes unmanageable computationally and logistically for the computing resources available to the average scientist. Here we present TopoDiff, a framework for a generalized. automated workflow that requires minimal input from the end user about a study site, and utilizes cloud computing resources to provide a temporally sorted and differenced dataset, ready for geostatistical analysis. This hands-off approach allows the end user to focus on the science, without having to manage thousands of files, or petabytes of data. At the same time, TopoDiff provides a consistent and accurate workflow for image sorting, selection, and co-registration enabling cross-comparisons between research projects.

  16. Extraction of Dems and Orthoimages from Archive Aerial Imagery to Support Project Planning in Civil Engineering

    Science.gov (United States)

    Cogliati, M.; Tonelli, E.; Battaglia, D.; Scaioni, M.

    2017-12-01

    Archive aerial photos represent a valuable heritage to provide information about land content and topography in the past years. Today, the availability of low-cost and open-source solutions for photogrammetric processing of close-range and drone images offers the chance to provide outputs such as DEM's and orthoimages in easy way. This paper is aimed at demonstrating somehow and to which level of accuracy digitized archive aerial photos may be used within a such kind of low-cost software (Agisoft Photoscan Professional®) to generate photogrammetric outputs. Different steps of the photogrammetric processing workflow are presented and discussed. The main conclusion is that this procedure may come to provide some final products, which however do not feature the high accuracy and resolution that may be obtained using high-end photogrammetric software packages specifically designed for aerial survey projects. In the last part a case study is presented about the use of four-epoch archive of aerial images to analyze the area where a tunnel has to be excavated.

  17. Waste incineration on its way to the power plants; Muellverbrennung auf dem Weg zum Kraftwerk

    Energy Technology Data Exchange (ETDEWEB)

    Reich, J. [STEAG encotec GmbH, Essen (Germany); Neukirchen, B. [STEAG AG, Essen (Germany)

    2004-07-01

    Looking at the year 2005 and the end of disposal of untreated domestic waste the politic hopes that the prognosticated lack of waste treatment capacity is remedied by coal-fired power plants. The classical municipal waste incinerators by contrast want to get recognition as energetic recycler in comparison with power stations. The decision of the European Court of Justice concerning recycling and disposal of domestic waste by incineration has started the discussion and competition on fuel-rich commercial waste. Are municipal waste incineration plants power stations or must power plants be regarded as incinerators? These questions are still open. (orig.) [German] Mit Blick auf das Jahr 2005 und das Ende der Ablagerung von unbehandeltem Siedlungsabfall hofft die Politik, dass der prognostizierte Mangel an Vorbehandlungskapazitaeten von den Kohlekraftwerken behoben wird. Die klassischen Muellverbrennungsanlagen wollen dagegen mit dem Kraftwerksvergleich die Anerkennung als energetische Verwerter erreichen. Das EuGH-Urteil zur Verwertung oder Beseitigung von Siedlungsabfall durch Verbrennen hat in diesem Jahr die Diskussion und den Kampf um den heizwertreichen Gewerbeabfall angeheizt. Die Frage, wie weit in Zukunft die Muellverbrennungsanlagen als Kraftwerke, aber auch die Kraftwerke als Muellverbrennungsanlagen angesehen werden muessen, ist noch offen. (orig.)

  18. DEM simulation of particle mixing for optimizing the overcoating drum in HTR fuel fabrication

    Science.gov (United States)

    Liu, Malin; Lu, Zhengming; Liu, Bing; Shao, Youlin

    2013-06-01

    The rotating drum was used for overcoating coated fuel particles in HTR fuel fabrication process. All the coated particles should be adhered to equal amount of graphite powder, which means that the particle should be mixed quickly in both radial and axial directions. This paper investigated the particle flow dynamics and mixing behavior in different regimes using the discrete element method (DEM). By varying the rotation speed, different flow regimes such as slumping, rolling, cascading, cataracting, centrifuging were produced. The mixing entropy based on radial and axial grid was introduced to describe the radial and axial mixing behaviors. From simulation results, it was found that the radial mixing can be achieved in the cascading regime more quickly than the slumping, rolling and centrifuging regimes, but the traditional rotating drum without internal components can not achieve the requirements of axial mixing and should be improved. Three different structures of internal components are proposed and simulated. The new V-shaped deflectors were found to achieve a quick axial mixing behavior and uniform axial distribution in the rotating drum based on simulation results. At last, the superiority was validated by experimental results, and the new V-shaped deflectors were used in the industrial production of the overcoating coated fuel particles in HTR fuel fabrication process.

  19. Element soil behaviour during pile installation simulated by 2D-DEM

    Science.gov (United States)

    Ji, Xiaohui; Cheng, Yi Pik; Liu, Junwei

    2017-06-01

    The estimation of the skin friction of onshore or offshore piles in sand is still a difficult problem for geotechnical engineers. It has been accepted by many researchers that the mechanism of driving piles in the soil has shared some similarities with that of an element shear test under the constant normal stiffness (CNS) condition. This paper describes the behaviour of an element of soil next to a pile during the process of pile penetration into dense fine sand using the 2D-DEM numerical simulation software. A new CNS servo was added to the horizontal boundary while maintaining the vertical stress constant. This should simulate the soil in a similar manner to that of a CNS pile-soil interface shear test, but allowing the vertical stress to remain constant which is more realistic to the field situation. Shear behaviours observed in these simulations were very similar to the results from previous researchers' lab shearing tests. With the normal stress and shear stress obtained from the virtual models, the friction angle and the shaft friction factor β mentioned in the API-2007 offshore pile design guideline were calculated and compared with the API recommended values.

  20. Element soil behaviour during pile installation simulated by 2D-DEM

    Directory of Open Access Journals (Sweden)

    Ji Xiaohui

    2017-01-01

    Full Text Available The estimation of the skin friction of onshore or offshore piles in sand is still a difficult problem for geotechnical engineers. It has been accepted by many researchers that the mechanism of driving piles in the soil has shared some similarities with that of an element shear test under the constant normal stiffness (CNS condition. This paper describes the behaviour of an element of soil next to a pile during the process of pile penetration into dense fine sand using the 2D-DEM numerical simulation software. A new CNS servo was added to the horizontal boundary while maintaining the vertical stress constant. This should simulate the soil in a similar manner to that of a CNS pile-soil interface shear test, but allowing the vertical stress to remain constant which is more realistic to the field situation. Shear behaviours observed in these simulations were very similar to the results from previous researchers’ lab shearing tests. With the normal stress and shear stress obtained from the virtual models, the friction angle and the shaft friction factor β mentioned in the API-2007 offshore pile design guideline were calculated and compared with the API recommended values.

  1. Effect of Nonsmooth Nose Surface of the Projectile on Penetration Using DEM Simulation

    Directory of Open Access Journals (Sweden)

    Jing Han

    2017-01-01

    Full Text Available The nonsmooth body surface of the reptile in nature plays an important role in reduction of resistance and friction when it lives in a soil environment. To consider whether it was feasible for improving the performance of penetrating projectile we investigated the influence of the convex as one of nonsmooth surfaces for the nose of projectile. A numerical simulation study of the projectile against the concrete target was developed based on the discrete element method (DEM. The results show that the convex nose surface of the projectile is beneficial for reducing the penetration resistance greatly, which is also validated by the experiments. Compared to the traditional smooth nose structure, the main reason of difference is due to the local contact normal pressure, which increases dramatically due to the abrupt change of curvature caused by the convex at the same condition. Accordingly, the broken particles of the concrete target obtain more kinetic energy and their average radial flow velocities will drastically increase simultaneously, which is in favor of decreasing the interface friction and the compaction density of concrete target around the nose of projectile.

  2. Particle–Mixing Simulations Using DEM and Comparison of the Performance of Mixing Indices

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Migyung [Tongmyong Univ., Busan (Korea, Republic of)

    2017-02-15

    Mixing of molecular grains having different characteristics is very important in many industries such as the food and pharmaceutical industries. With the development of computer simulations, it is common practice to find the optimal mixing conditions through a simulation before the actual mixing task to estimate the proper level of mixing. Accordingly, there has been an increasing need for a mixing index to measure the mix of particles in the simulation process. Mixing indices, which have been widely used so far, can largely be classified into two types: first is the statistical-based mixing index, which is prepared using the sampling method, and the second is the mixing index that is prepared using all the particles. In this paper, we calculated mixing indices in different ways for the data in the course of mixing the particles using the DEM simulation. Additionally, we compared the performance, advantages, and disadvantages of each mixing index. Therefore, I propose a standard that can be used to select an appropriate mixing index.

  3. Asperity Degradation and Damage in the Direct Shear Test: A Hybrid FEM/DEM Approach

    Science.gov (United States)

    Karami, A.; Stead, D.

    2008-04-01

    This paper investigates the processes of joint surface damage and near-surface intact rock tensile failure using a hybrid FEM/DEM code. Selected Barton and Choubey JRC profiles were simulated in direct shear tests and the surface damage mechanisms investigated in terms of joint surface wear or tensile fracturing of intact rock along the joint plane. Shear strength and displacement profiles for each joint profile are numerically simulated. Numerical results agree closely with published experimental observations. Furthermore, results show that dilation along the joint is controlled dominantly by the joint surface geometry and the applied normal stress. Significant dilation is expected to occur where there is a large asperity provided the applied normal stress is low. In this case, joint surface damage is limited to surface wear. In contrast, when the applied normal stress is high, dilation will be low and damage is composed of both surface wear and asperity breakage through near-joint-surface intact rock tensile failure. Local joint dilation angles vary in proportion to the magnitude of the dilation. Several joint profiles with different geometrical configurations were simulated within a slope and the possible modes of joint surface damage were investigated. It was found that due to low normal stresses acting on the joint surfaces within a slope the dominant mode of joint surface damage is by yielding and surface wear of asperities.

  4. Methodological application so as to obtain digital elevation models DEM in wetland areas

    International Nuclear Information System (INIS)

    Quintero, Deiby A; Montoya V, Diana M; Betancur, Teresita

    2009-01-01

    In order to understand hydrological systems and the description of flow processes that occur among its components it is essential to have a physiographic description that morphometric and relief characteristics. When local studies are performed, the basic cartography available, in the best case 1:25,000 scale, tends not to obey the needs required to represent the water dynamics that characterize the interactions between streams, aquifers and lenticular water bodies in flat zones particularly in those where there are wetlands localized in ancient F100D plains of rivers. A lack of financial resources is the principal obstacle to acquiring; information that is current and sufficient for the scale of the project. Geomorphologic conditions of flat relief zones are a good alternative for the construction of the new data. Using the basic cartography available and the new data, it is possible to obtain DEMs that are improved and consistent with the dynamics of surface and groundwater flows in the hydrological system. To accomplish this one must use spatial modeling tools coupled with Geographic Information System - GIS. This article present a methodological application for the region surrounding the catchment of wetland Cienaga Colombia in the Bajo Cauca region of Antioquia.

  5. Development of a coupled discrete element (DEM)-smoothed particle hydrodynamics (SPH) simulation method for polyhedral particles

    Science.gov (United States)

    Nassauer, Benjamin; Liedke, Thomas; Kuna, Meinhard

    2016-03-01

    In the present paper, the direct coupling of a discrete element method (DEM) with polyhedral particles and smoothed particle hydrodynamics (SPH) is presented. The two simulation techniques are fully coupled in both ways through interaction forces between the solid DEM particles and the fluid SPH particles. Thus this simulation method provides the possibility to simulate the individual movement of polyhedral, sharp-edged particles as well as the flow field around these particles in fluid-saturated granular matter which occurs in many technical processes e.g. wire sawing, grinding or lapping. The coupled method is exemplified and validated by the simulation of a particle in a shear flow, which shows good agreement with analytical solutions.

  6. A GPU-Based Parallel Procedure for Nonlinear Analysis of Complex Structures Using a Coupled FEM/DEM Approach

    Directory of Open Access Journals (Sweden)

    Lixiang Wang

    2013-01-01

    Full Text Available This study reports the GPU parallelization of complex three-dimensional software for nonlinear analysis of concrete structures. It focuses on coupled thermomechanical analysis of complex structures. A coupled FEM/DEM approach (CDEM is given from a fundamental theoretical viewpoint. As the modeling of a large structure by means of FEM/DEM may lead to prohibitive computation times, a parallelization strategy is required. With the substantial development of computer science, a GPU-based parallel procedure is implemented. A comparative study between the GPU and CPU computation results is presented, and the runtimes and speedups are analyzed. The results show that dramatic performance improvements are gained from GPU parallelization.

  7. Direct micromechanics derivation and DEM confirmation of the elastic moduli of isotropic particulate materials: Part I No particle rotation

    Science.gov (United States)

    Fleischmann, J. A.; Drugan, W. J.; Plesha, M. E.

    2013-07-01

    We derive the macroscopic elastic moduli of a statistically isotropic particulate aggregate material via the homogenization methods of Voigt (1928) (kinematic hypothesis), Reuss (1929) (static hypothesis), and Hershey (1954) and Kröner (1958) (self-consistent hypothesis), originally developed to treat crystalline materials, from the directionally averaged elastic moduli of three regular cubic packings of uniform spheres. We determine analytical expressions for these macroscopic elastic moduli in terms of the (linearized) elastic inter-particle contact stiffnesses on the microscale under the three homogenization assumptions for the three cubic packings (simple, body-centered, and face-centered), assuming no particle rotation. To test these results and those in the literature, we perform numerical simulations using the discrete element method (DEM) to measure the overall elastic moduli of large samples of randomly packed uniform spheres with constant normal and tangential contact stiffnesses (linear spring model). The beauty of DEM is that simulations can be run with particle rotation either prohibited or unrestrained. In this first part of our two-part series of papers, we perform DEM simulations with particle rotation prohibited, and we compare these results with our theoretical results that assumed no particle rotation. We show that the self-consistent homogenization assumption applied to the locally body-centered cubic (BCC) packing most accurately predicts the measured values of the overall elastic moduli obtained from the DEM simulations, in particular Poisson's ratio. Our new analytical self-consistent results lead to significantly better predictions of Poisson's ratio than all prior published theoretical results. Moreover, our results are based on a direct micromechanics analysis of specific geometrical packings of uniform spheres, in contrast to all prior theoretical analyses, which were based on difficult-to-verify hypotheses involving overall inter

  8. Extraction of multi-scale landslide morphological features based on local Gi* using airborne LiDAR-derived DEM

    Science.gov (United States)

    Shi, Wenzhong; Deng, Susu; Xu, Wenbing

    2018-02-01

    For automatic landslide detection, landslide morphological features should be quantitatively expressed and extracted. High-resolution Digital Elevation Models (DEMs) derived from airborne Light Detection and Ranging (LiDAR) data allow fine-scale morphological features to be extracted, but noise in DEMs influences morphological feature extraction, and the multi-scale nature of landslide features should be considered. This paper proposes a method to extract landslide morphological features characterized by homogeneous spatial patterns. Both profile and tangential curvature are utilized to quantify land surface morphology, and a local Gi* statistic is calculated for each cell to identify significant patterns of clustering of similar morphometric values. The method was tested on both synthetic surfaces simulating natural terrain and airborne LiDAR data acquired over an area dominated by shallow debris slides and flows. The test results of the synthetic data indicate that the concave and convex morphologies of the simulated terrain features at different scales and distinctness could be recognized using the proposed method, even when random noise was added to the synthetic data. In the test area, cells with large local Gi* values were extracted at a specified significance level from the profile and the tangential curvature image generated from the LiDAR-derived 1-m DEM. The morphologies of landslide main scarps, source areas and trails were clearly indicated, and the morphological features were represented by clusters of extracted cells. A comparison with the morphological feature extraction method based on curvature thresholds proved the proposed method's robustness to DEM noise. When verified against a landslide inventory, the morphological features of almost all recent ( 10 years) landslides were extracted. This finding indicates that the proposed method can facilitate landslide detection, although the cell clusters extracted from curvature images should be filtered

  9. GIS-based debris flow source and runout susceptibility assessment from DEM data – a case study in NW Nicaragua

    Directory of Open Access Journals (Sweden)

    J. M. Vilaplana

    2007-11-01

    Full Text Available In October 1998, Hurricane Mitch triggered numerous landslides (mainly debris flows in Honduras and Nicaragua, resulting in a high death toll and in considerable damage to property. The potential application of relatively simple and affordable spatial prediction models for landslide hazard mapping in developing countries was studied. Our attention was focused on a region in NW Nicaragua, one of the most severely hit places during the Mitch event. A landslide map was obtained at 1:10 000 scale in a Geographic Information System (GIS environment from the interpretation of aerial photographs and detailed field work. In this map the terrain failure zones were distinguished from the areas within the reach of the mobilized materials. A Digital Elevation Model (DEM with 20 m×20 m of pixel size was also employed in the study area. A comparative analysis of the terrain failures caused by Hurricane Mitch and a selection of 4 terrain factors extracted from the DEM which, contributed to the terrain instability, was carried out. Land propensity to failure was determined with the aid of a bivariate analysis and GIS tools in a terrain failure susceptibility map. In order to estimate the areas that could be affected by the path or deposition of the mobilized materials, we considered the fact that under intense rainfall events debris flows tend to travel long distances following the maximum slope and merging with the drainage network. Using the TauDEM extension for ArcGIS software we generated automatically flow lines following the maximum slope in the DEM starting from the areas prone to failure in the terrain failure susceptibility map. The areas crossed by the flow lines from each terrain failure susceptibility class correspond to the runout susceptibility classes represented in a runout susceptibility map. The study of terrain failure and runout susceptibility enabled us to obtain a spatial prediction for landslides, which could contribute to landslide risk

  10. Dementia Population Risk Tool (DemPoRT): study protocol for a predictive algorithm assessing dementia risk in the community

    OpenAIRE

    Fisher, Stacey; Hsu, Amy; Mojaverian, Nassim; Taljaard, Monica; Huyer, Gregory; Manuel, Douglas G; Tanuseputro, Peter

    2017-01-01

    Introduction The burden of disease from dementia is a growing global concern as incidence increases dramatically with age, and average life expectancy has been increasing around the world. Planning for an ageing population requires reliable projections of dementia prevalence; however, existing population projections are simple and have poor predictive accuracy. The Dementia Population Risk Tool (DemPoRT) will predict incidence of dementia in the population setting using multivariable modellin...

  11. Thetalifts von Poincaré- und Eisensteinreihen und zugehörige Zetafunktionen auf dem dreidimensionalen hyperbolischen Raum

    OpenAIRE

    Dickhut, B. (Barbara)

    2003-01-01

    Bildet man den Thetalift einer auf dem oberen Halbraum definierten Poincaré-Reihe mit einer geeigneten Siegelschen Thetafunktion, so stellt sich eine Zetafunktion ein. Diese kann nach geeigneter Parametrisierung als Poincaré-Reihe bezüglich des hyperbolischen Abstands geschrieben werden. Weiter wird die Spektralzerlegung der Zetafunktion angegeben und ihre meromorphe Fortsetzbarkeit auf die komplexe Ebene bewiesen. Es ergibt sich eine verallgemeinerte Koeffizientenformel für die Fourierkoeffi...

  12. GIS-based debris flow source and runout susceptibility assessment from DEM data - a case study in NW Nicaragua

    Science.gov (United States)

    Guinau, M.; Vilajosana, I.; Vilaplana, J. M.

    2007-11-01

    In October 1998, Hurricane Mitch triggered numerous landslides (mainly debris flows) in Honduras and Nicaragua, resulting in a high death toll and in considerable damage to property. The potential application of relatively simple and affordable spatial prediction models for landslide hazard mapping in developing countries was studied. Our attention was focused on a region in NW Nicaragua, one of the most severely hit places during the Mitch event. A landslide map was obtained at 1:10 000 scale in a Geographic Information System (GIS) environment from the interpretation of aerial photographs and detailed field work. In this map the terrain failure zones were distinguished from the areas within the reach of the mobilized materials. A Digital Elevation Model (DEM) with 20 m×20 m of pixel size was also employed in the study area. A comparative analysis of the terrain failures caused by Hurricane Mitch and a selection of 4 terrain factors extracted from the DEM which, contributed to the terrain instability, was carried out. Land propensity to failure was determined with the aid of a bivariate analysis and GIS tools in a terrain failure susceptibility map. In order to estimate the areas that could be affected by the path or deposition of the mobilized materials, we considered the fact that under intense rainfall events debris flows tend to travel long distances following the maximum slope and merging with the drainage network. Using the TauDEM extension for ArcGIS software we generated automatically flow lines following the maximum slope in the DEM starting from the areas prone to failure in the terrain failure susceptibility map. The areas crossed by the flow lines from each terrain failure susceptibility class correspond to the runout susceptibility classes represented in a runout susceptibility map. The study of terrain failure and runout susceptibility enabled us to obtain a spatial prediction for landslides, which could contribute to landslide risk mitigation.

  13. To the question on accuracy of forest heights’ measurements by the TanDEM-X radar interferometry data

    Directory of Open Access Journals (Sweden)

    T. N. Chimitdorzhiev

    2016-08-01

    Full Text Available The paper presents the validation results of the InSAR method for determining the forest canopy height, based on TanDEM-X and ALOS PALSAR data. The research conducted on the territory of the Baikal-Kudara forest area of the Republic of Buryatia (52°10'N, 106°48'E. Forest vegetation is represented mainly by conifers – pine, and spruce, with a small admixture of deciduous trees – aspen, birch, etc. The forest vegetation height was determined by subtracting the digital elevation model (DEM of the digital terrain model (DTM. DEM is built according to the L-band (wavelength of 23.5 cm ALOS PALSAR satellite with horizontal co-polarization mode. In the investigation it was assumed that a radar signal of ALOS PALSAR passes all forest thickness and reflected from the underlying surface, made it possible to recover terrain under forest canopy. DTM has been built using the TanDEM-X data (wavelength 3 cm. In this case, it was assumed that the radar echoes scattered from a some virtual phase centers of scattering surface, which characterizes the upper limit of the continuous forest canopy. To check the accuracy of satellite definitions of forest height in study area were made high-precision geodetic measurement of trees heights using electronic total station and the coordinates of geographic control points using differential GPS receivers. The discrepancy between the satellite and ground-based measurements at 11 test sites did not exceed 2 m, which is mainly due to the difference in measurement techniques: height of individual trees by ground methods and continuous forest canopy height using radar interferometry.

  14. Detecting Blind Fault with Fractal and Roughness Factors from High Resolution LiDAR DEM at Taiwan

    Science.gov (United States)

    Cheng, Y. S.; Yu, T. T.

    2014-12-01

    There is no obvious fault scarp associated with blind fault. The traditional method of mapping this unrevealed geological structure is the cluster of seismicity. Neither the seismic event nor the completeness of cluster could be captured by network to chart the location of the entire possible active blind fault within short period of time. High resolution DEM gathered by LiDAR could denote actual terrain information despite the existence of plantation. 1-meter interval DEM of mountain region at Taiwan is utilized by fractal, entropy and roughness calculating with MATLAB code. By jointing these handing, the regions of non-sediment deposit are charted automatically. Possible blind fault associated with Chia-Sen earthquake at southern Taiwan is served as testing ground. GIS layer help in removing the difference from various geological formation, then multi-resolution fractal index is computed around the target region. The type of fault movement controls distribution of fractal index number. The scale of blind fault governs degree of change in fractal index. Landslide induced by rainfall and/or earthquake possesses larger degree of geomorphology alteration than blind fault; special treatment in removing these phenomena is required. Highly weathered condition at Taiwan should erase the possible trace remained upon DEM from the ruptured of blind fault while reoccurrence interval is higher than hundreds of years. This is one of the obstacle in finding possible blind fault at Taiwan.

  15. A Multi-Scale Hybrid CFD-DEM-PBM Description of a Fluid-Bed Granulation Process

    Directory of Open Access Journals (Sweden)

    Maitraye Sen

    2014-01-01

    Full Text Available In this study, a hybrid multi-scale model has been developed for a continuous fluid bed wet granulation process by dynamically coupling computational fluid dynamics (CFD with a discrete element model (DEM and population balance model (PBM. In this process, the granules are formed by spraying the liquid binder on the fluidized powder bed. The fluid flow field has been solved implementing CFD principles and the behavior of the solid particles has been modeled using DEM techniques whereas the change in particle size has been quantified with the help of PBM. The liquid binder droplets have been modeled implicitly in DEM. A detailed understanding of the process aids in the development of better design, optimization and control strategies. The model predicts the evolution of important process variables (i.e., average particle diameter, particle size distribution (PSD and particle liquid content over time, which have qualitative similarity with experimentally observed trends. The advantage of incorporating the multi-scale approach is that the model can be used to study the distributions of collision frequencies, particle velocity and particle liquid content in different sections of the fluid bed granulator (FBG, in a more mechanistic manner.

  16. Uma revisão bibliográfica das principais demências que acometem a população brasileira

    Directory of Open Access Journals (Sweden)

    Claudia Lysia de O. Araújo

    2011-01-01

    Full Text Available Demência pode ser definida como uma síndrome caracterizada pelo declínio progressivo e global de memória e outras funções cognitivas. O presente trabalho é uma revisão bibliográfica que tem como objetivo identificar e apresentar a produção científica relacionada com a temática. O levantamento bibliográfico foi nas Bases de Dados da Biblioteca Virtual de Saúde - BIREME. Os tipos de demência aqui levadas em conta são: Demência de Alzheimer, Demência por Corpos de Lewy (DCL, Demência Frontotemporal (DFT e Demência Vascular. Nas demências, os fatores de risco variam de acordo com os estressores genéticos e ambientais, além da idade e histórico clínico, conforme cada indivíduo. As principais alterações cerebrais são: placas senis e emaranhados neurofibrilares, com comprometimento da neurotransmissão colinérgica e atrofia cerebral extensa. Na sua maior parte são patologias de início insidioso e deterioração progressiva. O primeiro sinal/sintoma é a perda da memória seguida de declínio cognitivo e funcional. Podem ser divididas em estágios conforme o acometimento. O diagnóstico é realizado por meio de história clínica, exames laboratoriais e de neuroimagem, exame clínico neurológico e exames neuropsicológicos. Conclui-se que ainda não se tem a cura das demências e que os estudos de células-tronco podem contribuir nesse sentido.

  17. Application of Bistatic TanDEM-X Interferometry to Measure Lava Flow Volume and Lava Extrusion Rates During the 2012-13 Tolbachik, Kamchatka Fissure Eruption

    Science.gov (United States)

    Kubanek, J.; Westerhaus, M.; Heck, B.

    2015-12-01

    Aerial imaging methods are a well approved source for mapping lava flows during eruptions and can serve as a base to assess the eruption dynamics and to determine the affected area. However, clouds and smoke often hinder optical systems like the Earth Observation Advanced Land Imager (EO-1-ALI, operated by NASA) to map lava flows properly, which hence affects its reliability. Furthermore, the amount of lava that is extruded during an eruption cannot be determined from optical images - however, it can significantly contribute to assess the accompanying hazard and risk. One way to monitor active lava flows is to quantify the topographic changes over time while using up-to-date high-resolution digital elevation models (DEMs). Whereas photogrammetric methods still fail when clouds and fume obstruct the sight, innovative radar satellite missions have the potential to generate high-resolution DEMs at any time. The innovative bistatic TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) satellite mission enables for the first time generating high-resolution DEMs from synthetic aperture radar satellite data repeatedly with reasonable costs and high resolution. The satellite mission consists of the two nearly identical satellites TerraSAR-X and TanDEM-X that build a large synthetic aperture radar interferometer with adaptable across- and along-track baselines aiming to generate topographic information globally. In the present study, we apply the TanDEM-X data to study the lava flows that were emplaced during the 2012-13 Tolbachik, Kamchatka fissure eruption. The eruption was composed of very fluid lava flows that effused along a northeast-southwest trending fissure. We used about fifteen bistatic data pairs to generate DEMs prior to, during, and after the eruption. The differencing of the DEMs enables mapping the lava flow field at different times. This allows measuring the extruded volume and to derive the changes in lava extrusion over time.

  18. Kompetenz verleiht Flügel. Ursprung und theoretische Grundlagen der Kompetenzorientierung. Ausgewählte Kapitel aus dem Buch: Der Siegeszug der Kompetenzen

    OpenAIRE

    Zaiser, Richard

    2016-01-01

    „Woher stammt die Kompetenzorientierung und Standardisierung?“ In diesem Text werden 18 ausgewählte Kapitel aus dem Buch (Der Siegeszug der Kompetenzen) angeboten. Das Bemühen um wissenschaftliche Genauigkeit, der Einbezug der persönlichen Erfahrung und Betroffenheit des Autors und der Versuch, ein komplexes und heikles Thema klar und verständlich darzustellen, sind drei besondere Aspekte, die den Text kennzeichnen. [...] Die Frage nach dem Ursprung (die im vorliegenden Text behandelt wird) w...

  19. Da Demência ao Transtorno Neurocognitivo Maior: Aspectos Atuais / From Dementia to Major Neurocognitive Disorder: Current Aspects

    Directory of Open Access Journals (Sweden)

    Rebeca Mendes de Paula Pessoa

    2016-12-01

    Full Text Available INTRODUÇÃO A demência (transtorno neurocognitivo maior é uma síndrome clínica, que cursa com deterioração dos domínios cognitivos, alterações de comportamento e prejuízo funcional.¹ Com o envelhecimento da população, o número de casos de demência tem aumentado progressivamente, principalmente nos países de média e baixa renda, elevando os gastos do sistema de saúde, com cuidados e tratamento.2-4 Desta forma, medidas de detecção do transtorno em estágios iniciais, prevenção e tratamento poderiam ser úteis e importantes na tentativa de amenizar os prejuízos e diminuir o número de casos.5 Epidemiologia Existe um aumento rápido e significativo da população brasileira acima de 60 anos. Dados do último Censo do Instituto Brasileiro de Geografia e Estatística de 2010 mostraram que existem mais de 20 milhões de brasileiros com idade superior a 60 anos, o que corresponde a 10,8% da população. Este percentual é mais que o dobro considerando os últimos 40 anos e em número absoluto esta população aumentou mais que quatro vezes. É esperado que esta faixa da população continue crescendo, com o aumento progressivo da expectativa de vida. Concomitantemente, mesmo em um quadro otimista com a melhora do controle dos fatores de risco cardiovasculares e mudança do estilo de vida e, consequente, diminuição da prevalência de demência como tem ocorrido em alguns países da Europa, o número absoluto de casos deve crescer e muito com o rápido envelhecimento da população brasileira. A prevalência de demência na população acima de 65 anos varia entre 5 e 7%, com maiores valores (8,5% encontrados na América Latina.3 Atualmente, existem mais de 30 milhões de pessoas com demência no mundo, 58% destas vivendo em países de baixa ou média renda como o Brasil, e estimativas apontam que este número pode duplicar em 20 anos.3-6

  20. Constructing a sequence of palaeoDEMs to obtain erosion rates in a drainage basin.N

    Science.gov (United States)

    Castelltort, F. Xavier; Carles Balasch, J.; Cirés, Jordi; Colombo, Ferran

    2017-04-01

    DEMs made in a present-day drainage basin, considering it as a geomorphic unit, represent the end result of a landscape evolution. This process has had to follow a model of erosion. Trying to establish a conceptual erosion model in landscape evolution represents the first difficulty in constructing a sequence of palaeoDEMs. But if one is able to do it, the result will be easier and believable. The next step to do is to make a catalogue of base level types present in the drainage basin. The list has to include elements with determinate position and elevation (x, y, z) from the centre of the basin until hillslopes. A list of base level types may contain fluvial terrace remnants, erosive surfaces, palaeosols, alluvial covers of glacis, alluvial fans, rockfalls, landslides and scree zones. It is very important to know the spatial and temporal relations between the elements of the list, even if they are disconnected by erosion processes. Relative chronologies have to be set for all elements of the catalogue, and as far as possible absolute chronologies. To do it,it is essential to have established first the spatial relations between them, including those elements that are gone. Moreover, it is also essential to have adapted all the elements to the conceptual erosion model proposed. In this step, it has to be kept in mind that erosion rates can be very different in determinate areas within the same geomorphic unit. Erosion processes are focused in specific zones while other areas are maintained in stability. A good technique to construct a palaeoDEM is to start making, by hand, a map of contour lines. At this point, it is valuable to use the elements' catalogue. The use of those elements belonging to the same palaeosurface will result in a map. Several maps can be obtained from a catalogue. Contour maps can be gridded into a 3D surface by means of a specific application and a set of surfaces will be obtained. Algebraic operations can be done with palaeoDEMs obtaining

  1. Spatial Prediction of Soil Depth from DEM-Based Landform Attributes in Headwater Hillslopes: Is An Optimal Resolution Exists?

    Science.gov (United States)

    Han, X.; Liu, J.; Li, X.

    2016-12-01

    Soil depth is an important input for hydrological modeling. Hence, hydrological studies and practices are now encountered with increasing demands for high quality soil survey maps. Therefore, many empirical-statistic models based on digital elevation model (DEM) derived landform attributes have been developed to predict soil depth. However, issues about what grid size should be adopted still confuse most researchers, especially on the condition that science development makes very high resolution (VHR) DEMs (e.g., sub-meter) becoming increasingly available. Consequently, researchers are more inclined to take advantage of VHR DEMs for modeling without test their practicability.To study the optimal grid size for soil depth prediction, we used a total station to obtain horizontal (x, y) and vertical (z) coordinates of 1676 surface points in H1 (0.42ha) and 970 points in H2 (0.31ha), and employed ordinary Kriging to achieve DEMs with nine horizontal resolutions (0.25m, 0.5m, 0.75m, 1m, 2m, 3.5m, 5m, 7,5m and 10m). Then nine primary and secondary topographic attributes were derived from each DEM and correlations were analyzed between soil depth and terrain attributes. The locations of soil depth sites were designed deliberately to cover typical geomorphic surfaces including: interfluve, backslope and channel positions by driving a 70-mm diameter hollow cylindrical gasoline drill. The model we adopted is artificial neural networks (ANN), with 53 locations in H1 as the input to train the model and 37 locations in H2 for model validation.Results indicate that soils in places such as convergent, larger contributing areas and higher TWI tend to be thicker. We also found that instead of the finest resolutions, grid sizes around 3.5m achieved the best predictions with lowest RMSE (root mean square error) and MAE (mean absolute error) values, inferring that a high spatial resolution does not necessarily achieved the highest results. Remarkably, grid size of 3.5m happens to be

  2. ANALYSIS OF INFLUENCE OF TERRAIN RELIEF ROUGHNESS ON DEM ACCURACY GENERATED FROM LIDAR IN THE CZECH REPUBLIC TERRITORY

    Directory of Open Access Journals (Sweden)

    M. Hubacek

    2016-06-01

    Full Text Available Digital elevation models are today a common part of geographic information systems and derived applications. The way of their creation is varied. It depends on the extent of area, required accuracy, delivery time, financial resources and technologies available. The first model covering the whole territory of the Czech Republic was created already in the early 1980's. Currently, the 5th DEM generation is being finished. Data collection for this model was realized using the airborne laser scanning which allowed creating the DEM of a new generation having the precision up to a decimetre. Model of such a precision expands the possibilities of employing the DEM and it also offers new opportunities for the use of elevation data especially in a domain of modelling the phenomena dependent on highly accurate data. The examples are precise modelling of hydrological phenomena, studying micro-relief objects, modelling the vehicle movement, detecting and describing historical changes of a landscape, designing constructions etc. Due to a nature of the technology used for collecting data and generating DEM, it is assumed that the resulting model achieves lower accuracy in areas covered by vegetation and in built-up areas. Therefore the verification of model accuracy was carried out in five selected areas in Moravia. The network of check points was established using a total station in each area. To determine the reference heights of check points, the known geodetic points whose heights were defined using levelling were used. Up to several thousands of points were surveyed in each area. Individual points were selected according to a different configuration of relief, different surface types, and different vegetation coverage. The sets of deviations were obtained by comparing the DEM 5G heights with reference heights which was followed by verification of tested elevation model. Results of the analysis showed that the model reaches generally higher precision than

  3. Linking flood peak, flood volume and inundation extent: a DEM-based approach

    Science.gov (United States)

    Rebolho, Cédric; Furusho-Percot, Carina; Blaquière, Simon; Brettschneider, Marco; Andréassian, Vazken

    2017-04-01

    Traditionally, flood inundation maps are computed based on the Shallow Water Equations (SWE) in one or two dimensions, with various simplifications that have proved to give good results. However, the complexity of the SWEs often requires a numerical resolution which can need long computing time, as well as detailed cross section data: this often results in restricting these models to rather small areas abundant with high quality data. This, along with the necessity for fast inundation mapping, are the reason why rapid inundation models are being designed, working for (almost) any river with a minimum amount of data and, above all, easily available data. Our model tries to follow this path by using a 100m DEM over France from which are extracted a drainage network and the associated drainage areas. It is based on two pre-existing methods: (1) SHYREG (Arnaud et al.,2013), a regionalized approach used to calculate the 2-year and 10-year flood quantiles (used as approximated bankfull flow and maximum discharge, respectively) for each river pixel of the DEM (below a 10 000 km2 drainage area) and (2) SOCOSE (Mailhol,1980), which gives, amongst other things, an empirical formula of a characteristic flood duration (for each pixel) based on catchment area, average precipitation and temperature. An overflow volume for each river pixel is extracted from a triangular shaped synthetic hydrograph designed with SHYREG quantiles and SOCOSE flood duration. The volume is then spread from downstream to upstream one river pixel at a time. When the entire hydrographic network is processed, the model stops and generates a map of potential inundation area associated with the 10-year flood quantile. Our model can also be calibrated using past-events inundation maps by adjusting two parameters, one which modifies the overflow duration, and the other, equivalent to a minimum drainage area for river pixels to be flooded. Thus, in calibration on a sample of 42 basins, the first draft of the

  4. Investigation on the cohesive silt/clay-particle sediment via the coupled CFD-DEM simulations

    Science.gov (United States)

    Xu, S.; Sun, H.; Sun, R.

    2017-12-01

    Sedimentation of silt/clay particles happens ubiquitously in nature and engineering field. There have been abundant studies focusing on the settling velocity of the cohesive particles, while studies on the sediment deposited from silt/clay irregular particles, including the vertical concentration profile of sediment and the various forces among the deposited particles are still lacking. This paper aims to investigate the above topics by employing the CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) simulations. In this work, we simulate the settling of the mono- and poly- dispersed silt/clay particles and mainly study the characteristics of the deposited cohesive sediment. We use the bonded particles to simulate the irregular silt/clay aggregates at the initial state and utilize the van der Waals force for all micro-particles to consider the cohesive force among silt/clay particles. The interparticle collision force and the fluid-particle interaction forces are also considered in our numerical model. The value of the mean structural density of cohesive sediment obtained from simulations is in good agreement with the previous research, and it is obviously smaller than no-cohesive sediment because of the existence of the silt/clay flocs. Moreover, the solid concentration of sediment increases with the growth of the depth. It is because the silt/clay flocs are more easily to break up due to the gradually increased submerged gravity of the deposited particles along the depth. We also obtain the noncontacted cohesive force and contact force profiles during the sedimentation and the self-weight consolidation process. The study of the concentration profile and the forces among silt/clay sediment will help to give an accurate initial condition for calculating the speed of the reconsolidation process by employing the artificial loads, which is necessary for practical designs of the land reclamation projects.

  5. Conversion analysis of a cylindrical biomass particle with a DEM-CFD coupling approach

    Directory of Open Access Journals (Sweden)

    Mohammad Mohseni

    2017-09-01

    Full Text Available Biomass as a renewable energy source has attracted more attention nowadays due to ecological and economical benefits. The main objective of this work is studying the biomass conversion with employing a DEM-CFD coupling approach. In this model, the solid particulates are considered as discrete elements coupled via heat, mass and momentum transfer to the surrounding gas as continuous phase. That is, a comprehensive three-dimensional numerical model is developed and applied to investigate the complex phenomena taking place during biomass conversion in a reactor. In this case, the physical and chemical processes as heat-up, drying, pyrolysis, gasification and combustion are taken into account based on the relevant homogeneous and heterogeneous reactions. This platform predicts the motion of discrete particles based on the newton's equations of motion; and the thermodynamic state of each particle is extended according to the related algorithms. The thermodynamic state estimates the temperature and species distributions inside the particle due to external heat sources and chemical reactions. The reaction rates are described with Arrhenius model, and the reactions in the gas phase are modeled using Partially Stirred Reactor (PaSR model with the standard k−ϵ turbulent model. The conductive and radiative heat transfer between particles as well as convective heat transfer between particles and gas phase are also observed. Due to layered behavior of biomass materials, the shape of particle is considered as cylindrical rather than spherical to predict more realistic results. In order to improve the numerical modeling of biomass conversion, a shrinkage model is also developed and validated with experimental data in literature.

  6. Erinnerungen. Aus dem Feldzuge der Franzosen in Russland unter Napoleon im Jahre 1812, von einem preußischen Bombardier, dem jetzigen Major Weinberger. Unveröffentlichtes Manuskript (1849), herausgegeben von Peter-Michael Berger

    OpenAIRE

    Weinberger, Friedrich Ludwig

    2012-01-01

    Friedrich Ludwig Weinberger (1794–1869) diente im Juni 1812 als Freiwilliger bei der Königsberger Garnisonsartillerie. Diese 400 Soldaten wurden von Napoleon in die Garde seiner Grande Armée zur Invasion Russlands zwangsweise eingegliedert. Als einer von nur 13 Überlebenden seiner Truppe kehrte Weinberger im März 1813 aus russischem Gewahrsam zurück. Über seine Erlebnisse beim Vormarsch, den Kämpfen, der Besetzung Moskaus, dem Rückzug und der Heimkehr verfasste er einen Bericht, den er m...

  7. Coupled LBM-DEM Three-phase Simulation on Gas Flux Seeping from Marine Sediment

    Science.gov (United States)

    Kano, Y.; Sato, T.

    2014-12-01

    One of the main issues of the geological storage of CO2 under the seabed is a risk of CO2 leakage. Once CO2seeps into the ocean, it rises in water column dissolving into seawater, which results in the acidification of seawater and/or returning to the air. Its behaviour significantly depends on flow rate and bubble size (Kano et al., 2009; Dewar et al., 2013). As for porous media, bubble size is generally predicted through simple force balance based on flow rate, surface tension and channel size which is estimated by porosity and grain size. However, in shallow marine sediments, grains could be mobilised and displaced by buoyant gas flow, which causes distinctive phenomena such as blow-out or formation of gas flow conduit. As a result, effective gas flux into seawater can be intermissive, and/or concentrated in narrow area (QICS, 2012; Kawada, 2013). Bubble size is also affected by these phenomena. To predict effective gas flux and bubble size into seawater, three-phase behaviour of gas-water-sediment grains should be revealed. In this presentation, we will report the results of gas-liquid-solid three-phase simulations and their comparisons with experimental and observation data. Size of solid particles is based on grain size composing marine sediments at some CCS project sites. Fluid-particle interactions are solved using the lattice Boltzmann method (LBM), while the particle-particle interactions are treated by coupling with the Discrete Element method (DEM). References: Dewar, M., Wei, W., McNeil, D., Chen, B., 2013. Small-scale modelling of the physiochemical impacts of CO2leaked from sub-seabed reservoirs or pipelines within the North Sea and surrounding waters. Marine Pollution Bulletin 73(2), 504-515. Kano, Y., Sato, T., Kita, J., Hirabayashi, S., Tabeta, S., 2009. Model prediction on the rise of pCO2 in uniform flows by leakage of CO2purposefully stored under the seabed. Int. J. Greenhouse Gas Control, Vol. 3(5), 617-625. Kawada, R. 2014. A study on the

  8. Relation between relief and crustal structure in the Cantabrian Mountains (Spain) using DEM-GIS analysis

    Science.gov (United States)

    Llana-Fúnez, Sergio; Rodríguez-Rodríguez, Laura; Ballesteros, Daniel; María Díaz-Díaz, Luis; Valenzuela, Pablo; López-Fernández, Carlos; José Domínguez-Cuesta, María; Meléndez, Mónica; Jiménez-Sánchez, Montserrat; Fernández-Viejo, Gabriela

    2017-04-01

    The Cantabrian Mountains show a linear E-W trend parallel to the northern coast of Iberia peninsula, from the Pyrenees to Galicia, where it looses its trend and linearity. The western end of the linear segment of the orogen coincides with a change in the style of structures, accommodating the N-S shortening during the convergence between Europe and Iberia plates. We study the relief of the 230 km-long segment of the linear range between the Cantabria and Galicia re- gions, up to 2,650 m altitude. The bulk trend of the orogeny is controlled by the orientation of alpine thrusts that accommodate the shortening in relation to plate convergence. The Alpine Orogeny produced crustal thickening and the present day topography. Crustal thickness varies from 30 km in Eastern Cantabrian Mountains to 45-55 km at the Middle part of these mountains. The collision between European and African plates localized in northern Iberia from the Eocene to Oligocene and later migrated to southern Iberia during the Miocene. No major tectonic convergence was accommodated in the Cantabrians Mountains since the Oligocene, entering the orogen an erosional phase since then. The GIS-analysis present here, using 5 and 25 m-resolution DEMs by the Spanish National Geographical Institute, aims to identify the major features and to characterize the overall relief of the Cantabrians Mountains. In our preliminary approach, we present swath profiles, major river basins, watershed, longitudinal profiles of major rivers and hypsometric curves from selected areas that cover the studied orogen segment. Major tectonic structures control the location and orientation of the main watershed of the mountain range, but also the orientation of some local watersheds, e.g. associated to the Llanera thrust or the Ventaniella (strike-slip) fault. An unexpected result is that the average altitude along the water divide is 1,500 m, regardless of the large differences in crustal thickness along the study area. Most

  9. Close range photogrammetry in soil erosion monitoring: Mass loss comparison between runoff plots and high resolution DEMs

    Science.gov (United States)

    Ahner, Mario; Seitz, Steffen; Scholten, Thomas; Song, Zhengshan; Schmidt, Karsten

    2017-04-01

    Soil erosion is a major environmental problem and can lead to severe negative impacts on terrestrial ecosystems. When raindrops hit a bare soil surface, the applied kinetic energy successively detaches soil particles. This rainsplash effect marks the initial stage of soil erosion, which can result in serious sediment losses with beginning surface runoff. Mini-runoff plots are often used to monitor soil erosion rates in comparative field experiments. However, this method is time-consuming, the sampling of detached soil is difficult and the accuracy heavily depends on thorough maintenance and control of the measurement setup. To optimize the acquisition of soil erosion data from splash and interrill processes, a digital method using close range photogrammetry was tested in 2015. Therefore, a photogrammetric workflow was applied to process high resolution digital elevation models (DEMs) from overlapping stereo-images. By calculating the differences between multi-temporal DEMs with a sub-millimetre resolution, the volume of detached sediment was assessed. We performed rainfall simulations with a single nozzle rainfall simulator and a light weight tent. Micro-scale runoff plots (ROPs, 0.4 m x 0.4 m) were used with two different treatments, namely a Hortic Anthrosol and sand (grain size 0.10-0.45 mm). Five repetitions of rainfall-exposure with an intensity of 60 mm h-1 were performed and each repetition divided into three intervals (0-15 min, 15-30 min and 30-60 min). Before the first and every following interval, a block of 25 stereo-images was acquired with a single lens reflex camera system and processed in Agisoft PhotoScan for DEM-generation. After every interval, the discharged sediment was dried and weighed in order to derive the ground-truth validation data for comparison. Results show that ROPs with the sand treatment generally showed a larger volume of detached sediment than the garden soil treatment. As sediment discharge increased, the modelled and measured

  10. Realistic representation of grain shapes in CFD-DEM simulations of sediment transport with a bonded-sphere approach

    Science.gov (United States)

    Sun, Rui; Xiao, Heng; Sun, Honglei

    2017-09-01

    Development of algorithms and growth of computational resources in the past decades have enabled simulations of sediment transport processes with unprecedented fidelities. The Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) is one of the high-fidelity approaches, where the motions of and collisions among the sediment grains as well as their interactions with surrounding fluids are resolved. In most DEM solvers the particles are modeled as soft spheres due to computational efficiency and implementation complexity considerations, although natural sediments are usually a mixture of non-spherical (e.g., disk-, blade-, and rod-shaped) particles. Previous attempts to extend sphere-based DEM to treat irregular particles neglected fluid-induced torques on particles, and the method lacked flexibility to handle sediments with an arbitrary mixture of particle shapes. In this contribution we proposed a simple, efficient approach to representing common sediment grain shapes with bonded spheres, where the fluid forces are computed and applied on each sphere. The proposed approach overcomes the aforementioned limitations of existing methods and has improved efficiency and flexibility over existing approaches. We use numerical simulations to demonstrate the merits and capability of the proposed method in predicting the falling characteristics, terminal velocity, threshold of incipient motion, and transport rate of natural sediments. The simulations show that the proposed method is a promising approach for faithful representation of natural sediment, which leads to accurate simulations of their transport dynamics. While this work focuses on non-cohesive sediments, the proposed method also opens the possibility for first-principle-based simulations of the flocculation and sedimentation dynamics of cohesive sediments. Elucidation of these physical mechanisms can provide much needed improvement on the prediction capability and physical understanding of muddy coast

  11. Direct micromechanics derivation and DEM confirmation of the elastic moduli of isotropic particulate materials:. Part II Particle rotation

    Science.gov (United States)

    Fleischmann, J. A.; Drugan, W. J.; Plesha, M. E.

    2013-07-01

    In Part I, Fleischmann et al. (2013), we performed theoretical analyses of three cubic packings of uniform spheres (simple, body-centered, and face-centered) assuming no particle rotation, employed these results to derive the effective elastic moduli for a statistically isotropic particulate material, and assessed these results by performing numerical discrete element method (DEM) simulations with particle rotations prohibited. In this second part, we explore the effect that particle rotation has on the overall elastic moduli of a statistically isotropic particulate material. We do this both theoretically, by re-analyzing the elementary cells of the three cubic packings with particle rotation allowed, which leads to the introduction of an internal parameter to measure zero-energy rotations at the local level, and numerically via DEM simulations in which particle rotation is unrestrained. We find that the effects of particle rotation cannot be neglected. For unrestrained particle rotation, we find that the self-consistent homogenization assumption applied to the locally body-centered cubic packing incorporating particle rotation effects most accurately predicts the measured values of the overall elastic moduli obtained from the DEM simulations, in particular Poisson's ratio. Our new self-consistent results and theoretical modeling of particle rotation effects together lead to significantly better theoretical predictions of Poisson's ratio than all prior published results. Moreover, our results are based on a direct micromechanics analysis of specific geometrical packings of uniform spheres, in contrast to prior theoretical analyses based on hypotheses involving overall inter-particle contact distributions. Thus, our results permit a direct assessment of the reasons for the theory-experiment discrepancies noted in the literature with regard to previous theoretical derivations of the macroscopic elastic moduli for particulate materials, and our new theoretical results

  12. Dem Assessment Derived from Close Range Photogrammetry: a Case Study from Kadavur Area, Karur District, Tamil Nadu, India

    Science.gov (United States)

    Anbarasan, S.; Sakthivel, R.

    2012-07-01

    Close-Range Photogrammetry is an accurate, cost effective technique of collecting measurements of real world objects and conditions, directly from photographs. Photogrammetry utilizes digital images to obtain accurate measurements and geometric data of the object or area of interest, in order to provide spatial information for Engineering design, spatial surveys or 3D modeling. The benefits of close-range Photogrammetry over other field procedures are purported to be: Increased accuracy; complete as-built information; reduced costs; reduced on-site time; and effective for small and large projects. The same basic principle of traditional Aerial Photogrammetry can be applied to stereoscopic pictures taken from lower altitudes or from the ground. Terrestrial, ground-based, and close-range are all descriptive terms that refer to photos taken with an object-to-camera distance less than 300m (1000 feet). (Matthews, N.A, 2008). Close range Photogrammetry is a technique for obtaining the geometric information (e.g. position, distance, size and shape) of any object in 3D space that was imaged on the two dimensional (2D) photos, (Wolf, P.R, et.al, 2000) DEM Generation requires many processing and computation, such as camera calibration, stereo matching, editing, and interpolation. All the mentioned steps contribute to the quality of DEM. Image on close range Photogrammetry can be captured using three kind of camera: metric camera, semi-metric camera, and non-metric camera (Hanke, K., et.al, 2002). In this paper DEM quality assessed at Kadavur area, Karur district, Tamil Naudu, India using Close Range Photogrammetry technique, Commercial Digital Camera and Leica Photogrammetry Suite.

  13. Recent glacier mass balance and area changes in the Kangri Karpo Mountains from DEMs and glacier inventories

    Directory of Open Access Journals (Sweden)

    K. Wu

    2018-01-01

    Full Text Available Due to the influence of the Indian monsoon, the Kangri Karpo Mountains in the south-east of the Tibetan Plateau is in the most humid and one of the most important and concentrated regions containing maritime (temperate glaciers. Glacier mass loss in the Kangri Karpo is an important contributor to global mean sea level rise, and changes run-off distribution, increasing the risk of glacial-lake outburst floods (GLOFs. Because of its inaccessibility and high labour costs, information about the Kangri Karpo glaciers is still limited. Using geodetic methods based on digital elevation models (DEMs derived from 1980 topographic maps from the Shuttle Radar Topography Mission (SRTM (2000 and from TerraSAR-X/TanDEM-X (2014, this study has determined glacier elevation changes. Glacier area and length changes between 1980 and 2015 were derived from topographical maps and Landsat TM/ETM+/OLI images. Results show that the Kangri Karpo contained 1166 glaciers with an area of 2048.50 ± 48.65 km2 in 2015. Ice cover diminished by 679.51 ± 59.49 km2 (24.9 ± 2.2 % or 0.71 ± 0.06 % a−1 from 1980 to 2015, although nine glaciers advanced. A glacierized area of 788.28 km2, derived from DEM differencing, experienced a mean mass loss of 0.46 ± 0.08 m w.e. a−1 from 1980 to 2014. Shrinkage and mass loss accelerated significantly from 2000 to 2015 compared to 1980–2000, consistent with a warming climate.

  14. Extraction of Terraces on the Loess Plateau from High-Resolution DEMs and Imagery Utilizing Object-Based Image Analysis

    Directory of Open Access Journals (Sweden)

    Hanqing Zhao

    2017-05-01

    Full Text Available Abstract: Terraces are typical artificial landforms on the Loess Plateau, with ecological functions in water and soil conservation, agricultural production, and biodiversity. Recording the spatial distribution of terraces is the basis of monitoring their extent and understanding their ecological effects. The current terrace extraction method mainly relies on high-resolution imagery, but its accuracy is limited due to vegetation coverage distorting the features of terraces in imagery. High-resolution topographic data reflecting the morphology of true terrace surfaces are needed. Terraces extraction on the Loess Plateau is challenging because of the complex terrain and diverse vegetation after the implementation of “vegetation recovery”. This study presents an automatic method of extracting terraces based on 1 m resolution digital elevation models (DEMs and 0.3 m resolution Worldview-3 imagery as auxiliary information used for object-based image analysis (OBIA. A multi-resolution segmentation method was used where slope, positive and negative terrain index (PN, accumulative curvature slope (AC, and slope of slope (SOS were determined as input layers for image segmentation by correlation analysis and Sheffield entropy method. The main classification features based on DEMs were chosen from the terrain features derived from terrain factors and texture features by gray-level co-occurrence matrix (GLCM analysis; subsequently, these features were determined by the importance analysis on classification and regression tree (CART analysis. Extraction rules based on DEMs were generated from the classification features with a total classification accuracy of 89.96%. The red band and near-infrared band of images were used to exclude construction land, which is easily confused with small-size terraces. As a result, the total classification accuracy was increased to 94%. The proposed method ensures comprehensive consideration of terrain, texture, shape, and

  15. Recent glacier mass balance and area changes in the Kangri Karpo Mountains from DEMs and glacier inventories

    Science.gov (United States)

    Wu, Kunpeng; Liu, Shiyin; Jiang, Zongli; Xu, Junli; Wei, Junfeng; Guo, Wanqin

    2018-01-01

    Due to the influence of the Indian monsoon, the Kangri Karpo Mountains in the south-east of the Tibetan Plateau is in the most humid and one of the most important and concentrated regions containing maritime (temperate) glaciers. Glacier mass loss in the Kangri Karpo is an important contributor to global mean sea level rise, and changes run-off distribution, increasing the risk of glacial-lake outburst floods (GLOFs). Because of its inaccessibility and high labour costs, information about the Kangri Karpo glaciers is still limited. Using geodetic methods based on digital elevation models (DEMs) derived from 1980 topographic maps from the Shuttle Radar Topography Mission (SRTM) (2000) and from TerraSAR-X/TanDEM-X (2014), this study has determined glacier elevation changes. Glacier area and length changes between 1980 and 2015 were derived from topographical maps and Landsat TM/ETM+/OLI images. Results show that the Kangri Karpo contained 1166 glaciers with an area of 2048.50 ± 48.65 km2 in 2015. Ice cover diminished by 679.51 ± 59.49 km2 (24.9 ± 2.2 %) or 0.71 ± 0.06 % a-1 from 1980 to 2015, although nine glaciers advanced. A glacierized area of 788.28 km2, derived from DEM differencing, experienced a mean mass loss of 0.46 ± 0.08 m w.e. a-1 from 1980 to 2014. Shrinkage and mass loss accelerated significantly from 2000 to 2015 compared to 1980-2000, consistent with a warming climate.

  16. Sensitivity of drainage morphometry based hydrological response (GIUH) of a river basin to the spatial resolution of DEM data

    Science.gov (United States)

    Sahoo, Ramendra; Jain, Vikrant

    2018-02-01

    Drainage network pattern and its associated morphometric ratios are some of the important plan form attributes of a drainage basin. Extraction of these attributes for any basin is usually done by spatial analysis of the elevation data of that basin. These planform attributes are further used as input data for studying numerous process-response interactions inside the physical premise of the basin. One of the important uses of the morphometric ratios is its usage in the derivation of hydrologic response of a basin using GIUH concept. Hence, accuracy of the basin hydrological response to any storm event depends upon the accuracy with which, the morphometric ratios can be estimated. This in turn, is affected by the spatial resolution of the source data, i.e. the digital elevation model (DEM). We have estimated the sensitivity of the morphometric ratios and the GIUH derived hydrograph parameters, to the resolution of source data using a 30 meter and a 90 meter DEM. The analysis has been carried out for 50 drainage basins in a mountainous catchment. A simple and comprehensive algorithm has been developed for estimation of the morphometric indices from a stream network. We have calculated all the morphometric parameters and the hydrograph parameters for each of these basins extracted from two different DEMs, with different spatial resolutions. Paired t-test and Sign test were used for the comparison. Our results didn't show any statistically significant difference among any of the parameters calculated from the two source data. Along with the comparative study, a first-hand empirical analysis about the frequency distribution of the morphometric and hydrologic response parameters has also been communicated. Further, a comparison with other hydrological models suggests that plan form morphometry based GIUH model is more consistent with resolution variability in comparison to topographic based hydrological model.

  17. Is it possible to prevent dementia? É possível prevenir o desenvolvimento da demência?

    Directory of Open Access Journals (Sweden)

    Nicola T Lautenschlager

    2002-04-01

    Full Text Available It is a robust trend that the World's population is growing older. The proportion of elderly compared to other age groups and especially the number of oldest old, above age 85 years, is steadily increasing. One of the most common disorders in later life is dementia, the major cause of functional disability and the need for long-term care. This has prompted intensive research towards identifying risk factors associated with dementia. For current therapeutic intervention of incipient dementia and future prevention trials it is important to identify subjects at high risk of developing dementia. This article reviews clinical and biological findings of the quest to identify pre-dementia in subjects with mild cognitive impairment. It gives an overview of the present knowledge in this area and discusses strategies that may be useful in delaying the onset of dementia.A população mundial está envelhecendo. A proporção de idosos cresce de forma constante quando comparada a outras faixas etárias, particularmente para o grupo com 85 ou mais anos de idade. Um dos problemas de saúde mais freqüentes em fases tardias da vida é a demência, uma das principais causas de perda da capacidade funcional em idosos que, com freqüência, requer assistência com cuidados básicos em longo prazo. Como conseqüência, várias pesquisas têm procurado estabelecer os fatores que aumentam o risco de demência. Do ponto de vista terapêutico, é importante ser capaz de identificar de forma confiável indivíduos com alto risco de desenvolver demência, já que esses pacientes seriam o principal alvo de intervenções clínicas desenhadas com o objetivo de preveni-la. Este artigo tem o objetivo de rever os principais achados clínicos e biológicos das pesquisas que tiveram como objetivo identificar "pré-demência" em pessoas com "comprometimento cognitivo leve". O artigo oferece uma visão panorâmica do conhecimento atual nessa área e discute estratégias que

  18. The Discrete Equation Method (DEM) for Fully Compressible Two-Phase Flows in Ducts of Spatially Varying Cross-Section

    Energy Technology Data Exchange (ETDEWEB)

    Ray A. Berry; Richard Saurel; Tamara Grimmett

    2009-07-01

    Typically, multiphase modeling begins with an averaged (or homogenized) system of partial differential equations (traditionally ill-posed) then discretizes this system to form a numerical scheme. Assuming that the ill-posedness problem is avoided by using a well-posed formulation such as the seven-equation model, this presents problems for the numerical approximation of non-conservative terms at discontinuities (interfaces, shocks) as well as unwieldy treatment of fluxes with seven waves. To solve interface problems without conservation errors and to avoid this questionable determination of average variables and the numerical approximation of the non-conservative terms associated with 2 velocity mixture flows we employ a new homogenization method known as the Discrete Equations Method (DEM). Contrary to conventional methods, the averaged equations for the mixture are not used, and this method directly obtains a (well-posed) discrete equation system from the single-phase system to produce a numerical scheme which accurately computes fluxes for arbitrary numbers of phases and solves non-conservative products. The method effectively uses a sequence of single phase Riemann equation solves. Phase interactions are accounted for by Riemann solvers at each interface. Flow topology can change with changing expressions for the fluxes. Non-conservative terms are correctly approximated. Some of the closure relations missing from the traditional approach are automatically obtained. Lastly, we can often times identify the continuous equation system, resulting from taking the continuous limit with weak wave assumptions, of the discrete equations. This can be very useful from a theoretical standpoint. As a first step toward implict integration of the DEM method in multidimensions, in this paper we construct a DEM model for the flow of two compressible phases in 1-D ducts of spatially varying cross-section to test this approach. To relieve time step size restrictions due to

  19. Can DEM time series produced by UAV be used to quantify diffuse erosion in an agricultural watershed?

    Science.gov (United States)

    Pineux, N.; Lisein, J.; Swerts, G.; Bielders, C. L.; Lejeune, P.; Colinet, G.; Degré, A.

    2017-03-01

    Erosion and deposition modelling should rely on field data. Currently these data are seldom available at large spatial scales and/or at high spatial resolution. In addition, conventional erosion monitoring approaches are labour intensive and costly. This calls for the development of new approaches for field erosion data acquisition. As a result of rapid technological developments and low cost, unmanned aerial vehicles (UAV) have recently become an attractive means of generating high resolution digital elevation models (DEMs). The use of UAV to observe and quantify gully erosion is now widely established. However, in some agro-pedological contexts, soil erosion results from multiple processes, including sheet and rill erosion, tillage erosion and erosion due to harvest of root crops. These diffuse erosion processes often represent a particular challenge because of the limited elevation changes they induce. In this study, we propose to assess the reliability and development perspectives of UAV to locate and quantify erosion and deposition in a context of an agricultural watershed with silt loam soils and a smooth relief. Erosion and deposition rates derived from high resolution DEM time series are compared to field measurements. The UAV technique demonstrates a high level of flexibility and can be used, for instance, after a major erosive event. It delivers a very high resolution DEM (pixel size: 6 cm) which allows us to compute high resolution runoff pathways. This could enable us to precisely locate runoff management practices such as fascines. Furthermore, the DEMs can be used diachronically to extract elevation differences before and after a strongly erosive rainfall and be validated by field measurements. While the analysis for this study was carried out over 2 years, we observed a tendency along the slope from erosion to deposition. Erosion and deposition patterns detected at the watershed scale are also promising. Nevertheless, further development in the

  20. EU Kids Online – Der sichere Umgang mit dem Internet. Österreich im europäischen Vergleich

    OpenAIRE

    Ingrid Paus-Hasebrink; Andrea Dürager

    2009-01-01

    Die Ergebnisse des dreijährigen europäischen Forschungsprojektes „EU Kids Online I“ zu Erfahrungen von Kindern und Jugendlichen mit dem Internet in Europa zeigen, dass die Forschungslage zu dieser Thematik in Österreich – aber auch in vielen anderen Ländern – als defizitär bezeichnet werden muss. Zudem zählt Österreich bei mittlerer Nutzungshäufigkeit des Internets zu den Ländern mit immerhin mittlerem Online-Risiko. Österreichische Eltern scheinen sich der mit der Internetnutzung ihrer Kinde...

  1. APLICAÇÕES DOS MODELOS DE ELEVAÇÃO SRTM EM GEOMORFOLOGIA / SRTM DEMs APPLICATIONS IN GEOMORPHOLOGY

    Directory of Open Access Journals (Sweden)

    Claudio Riccomini

    2008-08-01

    Full Text Available The Shuttle Radar Topography Mission (SRTM was realized to map the morphology of the Earth’scontinental areas between 60ºN and 54ºS, using radar interferometry. Application of Digital ElevationModels (DEMs in geomorphology allow calculation of topography-related variables with speed andprecision. In this paper, we present a general view of geomorphological studies supported by SRTM data,conducted within the Brazilian territory, as well as an appreciation of its limitations and future perspectives.

  2. Extracting Precise and Affordable Dems Despite of the Clouds. Ajax: the Joining of Radar and Optical Strengths

    Science.gov (United States)

    Cunin, 1 L.; Nonin, 2 P.; Janoth, 3 J.; Bernard, 4 M.

    2012-07-01

    On the one hand, onboard SPOT 5, the HRS instrument systematically collects stereopairs around the Globe since 2002. Each stereopair can encompass an area up to 600 km x 120 km within a single pass (i.e. 72 000 km² stereoscopic strips). Covering now more than 120 millions sq.km of the Earth landmasses, SPOT 5 stereoscopic imagery has become one of main satellite data sources for accurate DEM extraction, at least where the cloud coverage leaves a chance to do so ! On the other hand, the TerraSAR-X satellite, launched in June 2007, is able to collect radar data through the clouds in several modes. An approach to extract height information by radargrammetry was developed, and the commercial distribution of Digital Elevation Models based on TerraSAR-X StripMap and SpotLight Modes (resp. 3m and 1m resolution) has started in 2010. To improve the overall height accuracy of the DEM, acquisitions from both orbit directions are utilised, each point on the ground being thus imaged at least 4 times by TerraSAR-X. Since 2002, Spot Image and French National Cartographic Institute (IGN) are building a worldwide database called Elevation30/Reference3D™, which includes a Digital Elevation Model at 1-arc-second resolution (DTED level 2) extracted from HRS stereopairs. To answer the wide demand of precise DEMs over Tropical and Northern areas, frequently covered by clouds, a study was performed to integrate StripMap radargrammetric TerraSAR-X data into the Reference3D process, and two prototype products were issued, over Colombia and Congo areas. During this experiment, efforts have been made to stick to technical steps that could be integrated within a standardized production process, in order to keep offering affordable prices while maintaining a high standard of horizontal and vertical accuracy. The DEMs extracted from TerraSAR-X and HRS proved extremely consistent with each other, showing a mean difference of 0.80m. This allows to propose a unified Elevation30 product to the

  3. External Validation of the ASTER GDEM2, GMTED2010 and CGIAR-CSI- SRTM v4.1 Free Access Digital Elevation Models (DEMs in Tunisia and Algeria

    Directory of Open Access Journals (Sweden)

    Djamel Athmania

    2014-05-01

    Full Text Available Digital Elevation Models (DEMs including Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM, Shuttle Radar Topography Mission (SRTM, and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010 are freely available for nearly the entire earth’s surface. DEMs that are usually subject to errors need to be evaluated using reference elevation data of higher accuracy. This work was performed to assess the vertical accuracy of the ASTER GDEM version 2, (ASTER GDEM2, the Consultative Group on International Agriculture Research-Consortium for Spatial Information (CGIAR-CSI SRTM version 4.1 (SRTM v4.1 and the systematic subsample GMTED2010, at their original spatial resolution, using Global Navigation Satellite Systems (GNSS validation points. Two test sites, the Anaguid Saharan platform in southern Tunisia and the Tebessa basin in north eastern Algeria, were chosen for accuracy assessment of the above mentioned DEMs, based on geostatistical and statistical measurements. Within the geostatistical approach, empirical variograms of each DEM were compared with those of the GPS validation points. Statistical measures were computed from the elevation differences between the DEM pixel value and the corresponding GPS point. For each DEM, a Root Mean Square Error (RMSE was determined for model validation. In addition, statistical tools such as frequency histograms and Q-Q plots were used to evaluate error distributions in each DEM. The results indicate that the vertical accuracy of SRTM model is much higher than ASTER GDEM2 and GMTED2010 for both sites. In Anaguid test site, the vertical accuracy of SRTM is estimated 3.6 m (in terms of RMSE 5.3 m and 4.5 m for the ASTERGDEM2 and GMTED2010 DEMs, respectively. In Tebessa test site, the overall vertical accuracy shows a RMSE of 9.8 m, 8.3 m and 9.6 m for ASTER GDEM 2, SRTM and GMTED2010 DEM, respectively. This work is the first study to report the

  4. SediFoam: A general-purpose, open-source CFD-DEM solver for particle-laden flow with emphasis on sediment transport

    Science.gov (United States)

    Sun, Rui; Xiao, Heng

    2016-04-01

    With the growth of available computational resource, CFD-DEM (computational fluid dynamics-discrete element method) becomes an increasingly promising and feasible approach for the study of sediment transport. Several existing CFD-DEM solvers are applied in chemical engineering and mining industry. However, a robust CFD-DEM solver for the simulation of sediment transport is still desirable. In this work, the development of a three-dimensional, massively parallel, and open-source CFD-DEM solver SediFoam is detailed. This solver is built based on open-source solvers OpenFOAM and LAMMPS. OpenFOAM is a CFD toolbox that can perform three-dimensional fluid flow simulations on unstructured meshes; LAMMPS is a massively parallel DEM solver for molecular dynamics. Several validation tests of SediFoam are performed using cases of a wide range of complexities. The results obtained in the present simulations are consistent with those in the literature, which demonstrates the capability of SediFoam for sediment transport applications. In addition to the validation test, the parallel efficiency of SediFoam is studied to test the performance of the code for large-scale and complex simulations. The parallel efficiency tests show that the scalability of SediFoam is satisfactory in the simulations using up to O(107) particles.

  5. SveDem, the Swedish Dementia Registry - a tool for improving the quality of diagnostics, treatment and care of dementia patients in clinical practice.

    Directory of Open Access Journals (Sweden)

    Dorota Religa

    Full Text Available The Swedish Dementia Registry (SveDem was developed with the aim to improve the quality of diagnostic work-up, treatment and care of patients with dementia disorders in Sweden.SveDem is an internet based quality registry where several indicators can be followed over time. It includes information about the diagnostic work-up, medical treatment and community support (www.svedem.se. The patients are diagnosed and followed-up yearly in specialist units, primary care centres or in nursing homes.The database was initiated in May 2007 and covers almost all of Sweden. There were 28 722 patients registered with a mean age of 79.3 years during 2007-2012. Each participating unit obtains continuous online statistics from its own registrations and they can be compared with regional and national data. A report from SveDem is published yearly to inform medical and care professionals as well as political and administrative decision-makers about the current quality of diagnostics, treatment and care of patients with dementia disorders in Sweden.SveDem provides knowledge about current dementia care in Sweden and serves as a framework for ensuring the quality of diagnostics, treatment and care across the country. It also reflects changes in quality dementia care over time. Data from SveDem can be used to further develop the national guidelines for dementia and to generate new research hypotheses.

  6. Coupled DEM-CFD Analysis of the Initiation of Internal Instability in a Gap-Graded Granular Embankment Filter

    Science.gov (United States)

    Kawano, Kenichi; Shire, Tom; O'Sullivan, Catherine

    2017-06-01

    Internal instability is a form of internal erosion that can occur in embankment dams or flood embankments where the finer fraction of the material is washed out under the action of seepage flow; if undetected this process can progress to cause embankment collapse. Gap-graded materials are particularly susceptible. Skempton and Brogan [1] proposed that a key contributor to instability is the reduced stress transmitted by the finer fraction and that the magnitude of this reduced stress could be inferred from the hydraulic gradients observed at the initiation of particle migration in experiments. Here Skempton and Brogan's hypothesis is assessed at the particle scale using a discrete element method (DEM) model coupled with computational fluid dynamics (CFD). This contribution discusses validation of the coupled DEM-CFD software prior to describing the simulation of a permeameter experiment. The simulation generated particlescale data at the initiation of instability by considering a gap-graded sample subject to at a hydraulic gradient of 1.0 (upward flow). The results provide insight into the instability mechanism, most notably showing that while the particles that move under seepage flow do indeed transmit relatively small effective stress, a finite proportion of the particles that move transfer relatively large stresses.

  7. Effective Thermal Property Estimation of Unitary Pebble Beds Based on a CFD-DEM Coupled Method for a Fusion Blanket

    Science.gov (United States)

    Chen, Lei; Chen, Youhua; Huang, Kai; Liu, Songlin

    2015-12-01

    Lithium ceramic pebble beds have been considered in the solid blanket design for fusion reactors. To characterize the fusion solid blanket thermal performance, studies of the effective thermal properties, i.e. the effective thermal conductivity and heat transfer coefficient, of the pebble beds are necessary. In this paper, a 3D computational fluid dynamics discrete element method (CFD-DEM) coupled numerical model was proposed to simulate heat transfer and thereby estimate the effective thermal properties. The DEM was applied to produce a geometric topology of a prototypical blanket pebble bed by directly simulating the contact state of each individual particle using basic interaction laws. Based on this geometric topology, a CFD model was built to analyze the temperature distribution and obtain the effective thermal properties. The current numerical model was shown to be in good agreement with the existing experimental data for effective thermal conductivity available in the literature. supported by National Special Project for Magnetic Confined Nuclear Fusion Energy of China (Nos. 2013GB108004, 2015GB108002, 2014GB122000 and 2014GB119000), and National Natural Science Foundation of China (No. 11175207)

  8. How to bridge the gap between "unresolved" model and "resolved" model in CFD-DEM coupled method for sediment transport?

    Science.gov (United States)

    Liu, D.; Fu, X.; Liu, X.

    2016-12-01

    In nature, granular materials exist widely in water bodies. Understanding the fundamentals of solid-liquid two-phase flow, such as turbulent sediment-laden flow, is of importance for a wide range of applications. A coupling method combining computational fluid dynamics (CFD) and discrete element method (DEM) is now widely used for modeling such flows. In this method, when particles are significantly larger than the CFD cells, the fluid field around each particle should be fully resolved. On the other hand, the "unresolved" model is designed for the situation where particles are significantly smaller than the mesh cells. Using "unresolved" model, large amount of particles can be simulated simultaneously. However, there is a gap between these two situations when the size of DEM particles and CFD cell is in the same order of magnitude. In this work, the most commonly used void fraction models are tested with numerical sedimentation experiments. The range of applicability for each model is presented. Based on this, a new void fraction model, i.e., a modified version of "tri-linear" model, is proposed. Particular attention is paid to the smooth function of void fraction in order to avoid numerical instability. The results show good agreement with the experimental data and analytical solution for both single-particle motion and also group-particle motion, indicating great potential of the new void fraction model.

  9. Evaluation of the performance of the cross-flow air classifier in manufactured sand processing via CFD-DEM simulations

    Science.gov (United States)

    Petit, H. A.; Irassar, E. F.; Barbosa, M. R.

    2018-01-01

    Manufactured sands are particulate materials obtained as by product of rock crushing. Particle sizes in the sand can be as high as 6 mm and as low as a few microns. The concrete industry has been increasingly using these sands as fine aggregates to replace natural sands. The main shortcoming is the excess of particles smaller than Dust). This problem has been traditionally solved by a washing process. Air classification is being studied to replace the washing process and avoid the use of water. The complex classification process can only been understood with the aid of CFD-DEM simulations. This paper evaluates the applicability of a cross-flow air classifier to reduce the amount of dust in manufactured sands. Computational fluid dynamics (CFD) and discrete element modelling (DEM) were used for the assessment. Results show that the correct classification set up improves the size distribution of the raw materials. The cross-flow air classification is found to be influenced by the particle size distribution and the turbulence inside the chamber. The classifier can be re-designed to work at low inlet velocities to produce manufactured sand for the concrete industry.

  10. Co-seismic landslide topographic analysis based on multi-temporal DEM-A case study of the Wenchuan earthquake.

    Science.gov (United States)

    Ren, Zhikun; Zhang, Zhuqi; Dai, Fuchu; Yin, Jinhui; Zhang, Huiping

    2013-01-01

    Hillslope instability has been thought to be one of the most important factors for landslide susceptibility. In this study, we apply geomorphic analysis using multi-temporal DEM data and shake intensity analysis to evaluate the topographic characteristics of the landslide areas. There are many geomorphologic analysis methods such as roughness, slope aspect, which are also as useful as slope analysis. The analyses indicate that most of the co-seismic landslides occurred in regions with roughness, hillslope and slope aspect of >1.2, >30, and between 90 and 270, respectively. However, the intersection regions from the above three methods are more accurate than that derived by applying single topographic analysis method. The ground motion data indicates that the co-seismic landslides mainly occurred on the hanging wall side of Longmen Shan Thrust Belt within the up-down and horizontal peak ground acceleration (PGA) contour of 150 PGA and 200 gal, respectively. The comparisons of pre- and post-earthquake DEM data indicate that the medium roughness and slope increased, the roughest and steepest regions decreased after the Wenchuan earthquake. However, slope aspects did not even change. Our results indicate that co-seismic landslides mainly occurred at specific regions of high roughness, southward and steep sloping areas under strong ground motion. Co-seismic landslides significantly modified the local topography, especially the hillslope and roughness. The roughest relief and steepest slope are significantly smoothed; however, the medium relief and slope become rougher and steeper, respectively.

  11. Asia leaves Europe behind with Transrapid; Asien faehrt Europa mit dem Transrapid davon. Eine neue Technologie sucht ihre Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Voelkening, W.

    2003-07-01

    The path that led from the first groundbreaking maglev railway technology patent, granted to Herman Kemper on 14th August 1934 (DRP 643 316), to the first contract to build a maglev railway for public passenger services was a long and often arduous one. The contract was signed on 23rd January 2001 by the Shanghai Maglev Transport Development Co., Ltd. (SMTDC) and, for Germany, the Consortium Transrapid Project Shanghai. As a preliminary to this, an agreement had been reached on 30th June 2000 between the City of Shanghai and Transrapid International on a joint feasibility study for an approximately 30 km long Transrapid line linking the centre of Shanghai-Pudong with the new Pudong international Airport. (orig.) [German] Es war ein langer und manchmal recht beschwerlicher Weg vom ersten grundlegenden Patent zur Magnetbahntechnologie, das Hermann Kemper am 14. August 1934 erteilt wurde (DRP 643 316), bis hin zum ersten Vertrag zum Bau einer Magnetbahn fuer den oeffentlichen Personenverkehr. Dieser Vertrag wurde am 23. Januar 2001 in Shanghai abgeschlossen zwischen der 'Shanghai Maglev Transport Development Co., Ltd. (SMTDC)' und auf deutscher Seite dem 'Consortium Transrapid Project Shanghai'. Vorausgegangen war eine Vereinbarung zwischen der Stadt Shanghai und Transrapid International am 30. Juni 2000 ueber eine gemeinsam zu erarbeitende Durchfuehrbarkeitsstudie einer ca. 30 km langen Transrapidstrecke zwischen dem Zentrum von Shanghai-Pudong zum neuen Internationalen Flughafen Pudong. (orig.)

  12. Measuring Lava Flows With ArcticDEM: Application to the 2012-2013 Eruption of Tolbachik, Kamchatka

    Science.gov (United States)

    Dai, Chunli; Howat, Ian M.

    2017-12-01

    ArcticDEM is an open-access collection of high-resolution (2 m), repeat, digital surface models, created from submeter resolution, stereoscopic satellite imagery, covering the entire Arctic landmass. To demonstrate the application of this powerful new data source for measuring Earth surface change, we measure elevation changes resulting from the 2012-2013 eruption of Tolbachik volcano in Kamchatka, Russia, which reveals detailed variations in lava thickness. We estimate a total lava volume of 0.573 ± 0.007 km3 emplaced over an area of 45.8 km2 at a mean rate of 21 m3/s. Furthermore, the size and timing of eruptions over the past 2,000 years support the hypothesis that the combined eruptions of 1976-77 and 2012-2013 ejected much or all of the magma stored over the previous 1,000 years, so that a multicentury repose is expected. The approaches developed in this study will guide future, expanded applications of ArcticDEM to mapping terrain change.

  13. Coupled DEM-CFD Analysis of the Initiation of Internal Instability in a Gap-Graded Granular Embankment Filter

    Directory of Open Access Journals (Sweden)

    Kawano Kenichi

    2017-01-01

    Full Text Available Internal instability is a form of internal erosion that can occur in embankment dams or flood embankments where the finer fraction of the material is washed out under the action of seepage flow; if undetected this process can progress to cause embankment collapse. Gap-graded materials are particularly susceptible. Skempton and Brogan [1] proposed that a key contributor to instability is the reduced stress transmitted by the finer fraction and that the magnitude of this reduced stress could be inferred from the hydraulic gradients observed at the initiation of particle migration in experiments. Here Skempton and Brogan’s hypothesis is assessed at the particle scale using a discrete element method (DEM model coupled with computational fluid dynamics (CFD. This contribution discusses validation of the coupled DEM-CFD software prior to describing the simulation of a permeameter experiment. The simulation generated particlescale data at the initiation of instability by considering a gap-graded sample subject to at a hydraulic gradient of 1.0 (upward flow. The results provide insight into the instability mechanism, most notably showing that while the particles that move under seepage flow do indeed transmit relatively small effective stress, a finite proportion of the particles that move transfer relatively large stresses.

  14. A FEM-DEM technique for studying the motion of particles in non-Newtonian fluids. Application to the transport of drill cuttings in wellbores

    Science.gov (United States)

    Celigueta, Miguel Angel; Deshpande, Kedar M.; Latorre, Salvador; Oñate, Eugenio

    2016-04-01

    We present a procedure for coupling the finite element method (FEM) and the discrete element method (DEM) for analysis of the motion of particles in non-Newtonian fluids. Particles are assumed to be spherical and immersed in the fluid mesh. A new method for computing the drag force on the particles in a non-Newtonian fluid is presented. A drag force correction for non-spherical particles is proposed. The FEM-DEM coupling procedure is explained for Eulerian and Lagrangian flows, and the basic expressions of the discretized solution algorithm are given. The usefulness of the FEM-DEM technique is demonstrated in its application to the transport of drill cuttings in wellbores.

  15. An automated, open-source pipeline for mass production of digital elevation models (DEMs) from very-high-resolution commercial stereo satellite imagery

    Science.gov (United States)

    Shean, David E.; Alexandrov, Oleg; Moratto, Zachary M.; Smith, Benjamin E.; Joughin, Ian R.; Porter, Claire; Morin, Paul

    2016-06-01

    We adapted the automated, open source NASA Ames Stereo Pipeline (ASP) to generate digital elevation models (DEMs) and orthoimages from very-high-resolution (VHR) commercial imagery of the Earth. These modifications include support for rigorous and rational polynomial coefficient (RPC) sensor models, sensor geometry correction, bundle adjustment, point cloud co-registration, and significant improvements to the ASP code base. We outline a processing workflow for ˜0.5 m ground sample distance (GSD) DigitalGlobe WorldView-1 and WorldView-2 along-track stereo image data, with an overview of ASP capabilities, an evaluation of ASP correlator options, benchmark test results, and two case studies of DEM accuracy. Output DEM products are posted at ˜2 m with direct geolocation accuracy of scale batch processing in a high-performance computing environment. We are leveraging these resources to produce dense time series and regional mosaics for the Earth's polar regions.

  16. High-resolution DEMs for High-mountain Asia: A systematic, region-wide assessment of geodetic glacier mass balance and dynamics

    Science.gov (United States)

    Shean, D. E.; Arendt, A. A.; Osmanoglu, B.; Montesano, P.

    2017-12-01

    High Mountain Asia (HMA) constitutes the largest glacierized region outside of the Earth's polar regions. Although available observations are limited, long-term records indicate sustained regional glacier mass loss since 1850, with increased loss in recent decades. Recent satellite data (e.g., GRACE, ICESat-1) show spatially variable glacier mass balance, with significant mass loss in the Himalaya and Hindu Kush and slight mass gain in the Karakoram. We generated 4000 high-resolution digital elevation models (DEMs) from sub-meter commercial stereo imagery (DigitalGlobe WorldView/GeoEye) acquired over glaciers in High-mountain Asia from 2002-present (mostly 2013-present). We produced a regional 8-m DEM mosaic for 2015 and estimated 15-year geodetic mass balance for 40000 glaciers larger than 0.1 km2. We are combining with other regional DEM sources to systematically document the spatiotemporal evolution of glacier mass balance for the entire HMA region. We also generated monthly to interannual DEM and velocity time series for high-priority sites distributed across the region, with >15-20 DEMs available for some locations from 2010-present. These records document glacier dynamics, seasonal snow accumulation/redistribution, and processes that affect glacier mass balance (e.g., ice-cliff retreat, debris cover evolution). These efforts will provide basin-scale assessments of snow/ice melt runoff contributions for model cal/val and downstream water resources applications. We will continue processing all archived and newly available commercial stereo imagery for HMA, and will release all DEMs through the HiMAT DAAC.

  17. Die Struktur der Handgesten im indischen Tanz nach dem „Nāṭya-Śāstra“ des Bharata (NŚBh)

    OpenAIRE

    Müller, Biliana

    2008-01-01

    In der vorliegenden Untersuchung wird eine Strukturanalyse der Gestensprache im indischen Tanz nach einem schriftlich vorliegenden Text vorgeschlagen – dem neunten Kapitel des ‚Nāṭya-Śāstra‘ eines legendären Autors namens Bharata. Der untersuchte Text ist Zeugnis für ein Zeichensystem, das über mehr als zwei Jahrtausende als Basis für die symbolische Interaktion auf dem indischen Subkontinent gedient hat und heute in zahlreichen Variationen präsent ist. Dieses Zeichensystem ist im semiotische...

  18. Fusion of Multi-Source Satellite Data and DEMs to Create a New Glacier Inventory for Novaya Zemlya

    Directory of Open Access Journals (Sweden)

    Philipp Rastner

    2017-11-01

    Full Text Available Monitoring glacier changes in remote Arctic regions are strongly facilitated by satellite data. This is especially true for the Russian Arctic where recently increased optical and SAR satellite imagery (Landsat 8 OLI, Sentinel 1/2, and digital elevation models (TanDEM-X, ArcticDEM are becoming available. These datasets offer new possibilities to create high-quality glacier inventories. Here, we present a new glacier inventory derived from a fusion of multi-source satellite data for Novaya Zemlya in the Russian Arctic. We mainly used Landsat 8 OLI data to automatically map glaciers with the band ratio method. Missing debris-covered glacier parts and misclassified lakes were manually corrected. Whereas perennial snow fields were a major obstacle in glacier identification, seasonal snow was identified and removed using Landsat 5 TM scenes from the year 1998. Drainage basins were derived semi-automatically using the ArcticDEM (gap-filled by the ASTER GDEM V2 and manually corrected using fringes from ALOS PALSAR. The new glacier inventory gives a glacierized area of 22,379 ± 246.16 km2 with 1474 glacier entities >0.05 km2. The region is dominated by large glaciers, as 909 glaciers <0.5 km2 (62% by number cover only 156 ± 1.7 km2 or 0.7% of the area, whereas 49 glaciers >100 km2 (3.3% by number cover 18,724 ± 205.9 km2 or 84%. In total, 41 glaciers are marine terminating covering an area of 16,063.7 ± 118.8 km2. The mean elevation is 596 m for all glaciers in the study region (528 m in the northern part, 641 in the southern part. South-east (north-west facing glaciers cover >35% (20% of the area. For the smaller glaciers in the southern part we calculated an area loss of ~5% (52.5 ± 4.5 km2 from 2001 to 2016.

  19. Demência reversível e quedas associadas ao biperideno Reversible dementia and falls associated with biperiden

    Directory of Open Access Journals (Sweden)

    Julio César Rigo

    2006-01-01

    Full Text Available As drogas anticolinérgicas podem causar efeitos adversos, mais freqüentemente nos pacientes idosos. Relatamos um caso de demência reversível e quedas, associadas ao uso de biperideno. A paciente, com 82 anos, foi admitida em lar geriátrico devido a quedas freqüentes no domicílio, acentuado déficit cognitivo, tremores de extremidades ao movimento e perda de autonomia. Na verdade, era portadora de tremor essencial, que foi confundido com doença de Parkinson e tratado com biperideno; posteriormente, desenvolveu déficit cognitivo que foi erroneamente diagnosticado como demência do tipo Alzheimer. Após submeter-se à avaliação especializada, foi suspensa a droga anticolinérgica e houve reversão completa do quadro demencial; o tremor essencial foi controlado com uso de propranolol. Ao avaliar um paciente com déficit cognitivo, o clínico deve descartar possíveis causas de demência reversível, em especial, o grupo das iatrogênicas.Anticholinergic drugs may cause adverse effects, more often in the aged patients. We describe a case of reversible dementia and falls, associated with the use of biperiden. The patient was an 82-year old woman, admitted in a geriatric home because of frequent falls at home, progressive cognitive deficit and tremor of extremities with movement, in addition to remarkable loss of autonomy. As a matter of fact, she presented an essential tremor, which was mistakenly diagnosed as Parkinson disease and treated with biperiden; furthermore, she developed a drug-induced cognitive deficit, erroneously interpreted as Alzheimer disease. After submitted to the specialized evaluation, the anticholinergic drug was discontinued and there was a complete improvement of cognition changes; the essential tremor is under control with use of propranolol. When evaluating a patient with cognitive deficit, the clinician must discard possible causes of reversible dementia, especially the iatrogenic group.

  20. Bridging scale gaps between regional maps of forest aboveground biomass and field sampling plots using TanDEM-X data

    Science.gov (United States)

    Ni, W.; Zhang, Z.; Sun, G.

    2017-12-01

    Several large-scale maps of forest AGB have been released [1] [2] [3]. However, these existing global or regional datasets were only approximations based on combining land cover type and representative values instead of measurements of actual forest aboveground biomass or forest heights [4]. Rodríguez-Veiga et al[5] reported obvious discrepancies of existing forest biomass stock maps with in-situ observations in Mexico. One of the biggest challenges to the credibility of these maps comes from the scale gaps between the size of field sampling plots used to develop(or validate) estimation models and the pixel size of these maps and the availability of field sampling plots with sufficient size for the verification of these products [6]. It is time-consuming and labor-intensive to collect sufficient number of field sampling data over the plot size of the same as resolutions of regional maps. The smaller field sampling plots cannot fully represent the spatial heterogeneity of forest stands as shown in Figure 1. Forest AGB is directly determined by forest heights, diameter at breast height (DBH) of each tree, forest density and tree species. What measured in the field sampling are the geometrical characteristics of forest stands including the DBH, tree heights and forest densities. The LiDAR data is considered as the best dataset for the estimation of forest AGB. The main reason is that LiDAR can directly capture geometrical features of forest stands by its range detection capabilities.The remotely sensed dataset, which is capable of direct measurements of forest spatial structures, may serve as a ladder to bridge the scale gaps between the pixel size of regional maps of forest AGB and field sampling plots. Several researches report that TanDEM-X data can be used to characterize the forest spatial structures [7, 8]. In this study, the forest AGB map of northeast China were produced using ALOS/PALSAR data taking TanDEM-X data as a bridges. The TanDEM-X InSAR data used in

  1. Creating high-resolution bare-earth digital elevation models (DEMs) from stereo imagery in an area of densely vegetated deciduous forest using combinations of procedures designed for lidar point cloud filtering

    Science.gov (United States)

    DeWitt, Jessica D.; Warner, Timothy A.; Chirico, Peter G.; Bergstresser, Sarah E.

    2017-01-01

    For areas of the world that do not have access to lidar, fine-scale digital elevation models (DEMs) can be photogrammetrically created using globally available high-spatial resolution stereo satellite imagery. The resultant DEM is best termed a digital surface model (DSM) because it includes heights of surface features. In densely vegetated conditions, this inclusion can limit its usefulness in applications requiring a bare-earth DEM. This study explores the use of techniques designed for filtering lidar point clouds to mitigate the elevation artifacts caused by above ground features, within the context of a case study of Prince William Forest Park, Virginia, USA. The influences of land cover and leaf-on vs. leaf-off conditions are investigated, and the accuracy of the raw photogrammetric DSM extracted from leaf-on imagery was between that of a lidar bare-earth DEM and the Shuttle Radar Topography Mission DEM. Although the filtered leaf-on photogrammetric DEM retains some artifacts of the vegetation canopy and may not be useful for some applications, filtering procedures significantly improved the accuracy of the modeled terrain. The accuracy of the DSM extracted in leaf-off conditions was comparable in most areas to the lidar bare-earth DEM and filtering procedures resulted in accuracy comparable of that to the lidar DEM.

  2. A CFD-DEM study of single bubble formation in gas fluidization of spherical and non-spherical particles

    Directory of Open Access Journals (Sweden)

    Shrestha Siddhartha

    2017-01-01

    Full Text Available Bubble dynamics significantly affect the hydrodynamics of gas-solid fluidized bed since they influence the gas-solid mixing. In this study, simulations using CFD-DEM were carried out to characterize the bubble size and shape for a bubble formed at a single orifice in gas-solid fluidized bed. Impact of parameters such as jet velocity, orifice size and particle shape on bubble equivalent diameter and bubble aspect ratio were analysed and discussed. Bubble equivalent diameter was found to increase with increasing jet velocity, decreasing bed width to orifice width ratio, and particle shape deviating from spherical. The bubble shape illustrated by aspect ratio, was found to elongate more as it rise through the bed and then commence to expand horizontally after it was detached from the orifice. Aspect ratio was found to be closer to a circle for the bubble at higher jet velocity, lower orifice width to bed ratio and for non-spherical particles.

  3. A CFD-DEM study of single bubble formation in gas fluidization of spherical and non-spherical particles

    Science.gov (United States)

    Shrestha, Siddhartha; Zhou, Zongyan

    2017-06-01

    Bubble dynamics significantly affect the hydrodynamics of gas-solid fluidized bed since they influence the gas-solid mixing. In this study, simulations using CFD-DEM were carried out to characterize the bubble size and shape for a bubble formed at a single orifice in gas-solid fluidized bed. Impact of parameters such as jet velocity, orifice size and particle shape on bubble equivalent diameter and bubble aspect ratio were analysed and discussed. Bubble equivalent diameter was found to increase with increasing jet velocity, decreasing bed width to orifice width ratio, and particle shape deviating from spherical. The bubble shape illustrated by aspect ratio, was found to elongate more as it rise through the bed and then commence to expand horizontally after it was detached from the orifice. Aspect ratio was found to be closer to a circle for the bubble at higher jet velocity, lower orifice width to bed ratio and for non-spherical particles.

  4. Pollutants from road traffic and breathing problems in children; Schadstoffe aus dem Strassenverkehr und Atemwegsbeschwerden bei Kindern

    Energy Technology Data Exchange (ETDEWEB)

    Mutius, E. von [Muenchen Univ. (Germany). Dr. von Haunersche Kinderklinik

    1996-06-01

    So far, there ave been few studies on measurable health effects of emissions from road traffic. An analysis of the available studies yields no clear indication of a relationship between road traffic emissions and the incidence of asthma and allergies in infants. On the other hand, there are no valid data on individual pollutant exposure of infants in the framework of epidemiological studies which take account of other influencing factors.(orig./MG) [Deutsch] Der Frag, ob eine Schadstoffbelastung durch den Strassenverkehr einen messbaren schaedigenden Effekt auf die menschliche Gesundheit hat, ist bislang in wenigen Studien nachgegangen worden. Analysiert man die vorliegenden Studien, ergibt sich derzeit kein eindeutiger Hinweis auf einen starken Zusammenhang zwischen der Strassenverkehrsbelastung und dem Auftreten von Asthma und Allergien beim Kind. Allerdings fehlt es an validen Daten zur individuellen Schadstoffexposition bei Kindern im Rahmen epidemiologischer Studien, ie eine Beruecksichtigung anderer Einfluss- und Stoervariablen erlauben. (orig/MG)

  5. Drying of sewage sludge using the ECACTHERM {sup trademark} process; Trocknung von Abwasserschlaemmen mit dem ECACTHERM {sup trademark} Verfahren

    Energy Technology Data Exchange (ETDEWEB)

    Gerl, S. [Maschinenfabrik Gustav Eirich GmbH und Co KG, Hardheim (Germany)

    2003-07-01

    This is an established process in many fields of industry. For drying, superheated water vapour is introduced into a mechanically fluidized bed. The granulated end products are cooled in a vacuum using the cold generated by evaporation cooling. In partial vacuum and in a closed-loop process, drying and granulation take place in inert conditions, without unpleasant smell and with minimum energy consumption. (orig.) [German] Der EVACTHERM {sup trademark} Vakuumheissdampftrocknungsprozess in einem Eirich Mischreaktor ist seit vielen Jahren in den verschiedensten Industriebereichen zur Schlammaufbereitung erfolgreich im Einsatz. Die Trocknung erfolgt durch Einleitung von ueberhitztem Wasserdampf in ein mechanisch erzeugtes Wirbelbett. Die Kuehlung des granulierten Endproduktes wird durch Anlegen von Vakuum unter Ausnutzung der Verdampfungskuehlung erzielt. Durch die Aufbereitung im leichten Unterdruck und dem Betrieb in geschlossener Kreislauffuehrung mit ueberhitztem Dampf, erfolgt die Trocknung und Granulierung unter inerten Bedingungen, ohne Geruchsemissionen und bei minimalem Energieverbrauch. (orig.)

  6. Numerical Investigation of Simultaneously Deposition and Re-Entrainment Fouling Processes in Corrugated Tubes by Coupling CFD and DEM

    DEFF Research Database (Denmark)

    Hærvig, Jakob; Condra, Thomas Joseph; Sørensen, Kim

    The deposition of particulate fouling on flue gas heat exchanger surfaces results in decreased heat transfer. Even though an increasingly amount of work is done on the design of clean heat exchanger surfaces, the effect of fouling remains a challenge. As some heat exchanger designs are more prone...... to fouling deposit than others, detailed fouling considerations have to be taken into account in the initial design process of new heat exchangers. This study presents initial simulations of particulate fouling in the corrugated tube heat exchanger type. Using a mechanistic Euler-Lagrange approach, where...... Computational Fluid Dynamics (CFD) software OpenFOAM is coupled to the Discrete Element Method (DEM) software LIGGGHTS using the coupling software CFDEM. A four-way coupling is used to model fluid-particle and particle-particle interactions and thereby allowing for a particle fouling layer to build up along...

  7. O sujeito e o efeito da própria fala na afasia e na demência

    Directory of Open Access Journals (Sweden)

    Rosana Landi

    2010-12-01

    Full Text Available Este trabalho aborda uma questão suscitada pelo meu encontro com falas de sujeitos com demência e com afasia. Com Saussure, reconheço a enunciação da ordem própria da língua e assumo que a língua não é nomenclatura. Procuro fazer valer as leis de referência interna da linguagem, que deslocam o signo para o lugar de efeito de suas operações. Com base neste solo teórico, encontro nas “falas vazias”, falas plenas de uma verdade sobre a relação profunda e indissolúvel do sujeito com a linguagem.

  8. Dementia Population Risk Tool (DemPoRT): study protocol for a predictive algorithm assessing dementia risk in the community.

    Science.gov (United States)

    Fisher, Stacey; Hsu, Amy; Mojaverian, Nassim; Taljaard, Monica; Huyer, Gregory; Manuel, Douglas G; Tanuseputro, Peter

    2017-10-24

    The burden of disease from dementia is a growing global concern as incidence increases dramatically with age, and average life expectancy has been increasing around the world. Planning for an ageing population requires reliable projections of dementia prevalence; however, existing population projections are simple and have poor predictive accuracy. The Dementia Population Risk Tool (DemPoRT) will predict incidence of dementia in the population setting using multivariable modelling techniques and will be used to project dementia prevalence. The derivation cohort will consist of elderly Ontario respondents of the Canadian Community Health Survey (CCHS) (2001, 2003, 2005 and 2007; 18 764 males and 25 288 females). Prespecified predictors include sociodemographic, general health, behavioural, functional and health condition variables. Incident dementia will be identified through individual linkage of survey respondents to population-level administrative healthcare databases (1797 and 3281 events, and 117 795 and 166 573 person-years of follow-up, for males and females, respectively, until 31 March 2014). Using time of first dementia capture as the primary outcome and death as a competing risk, sex-specific proportional hazards regression models will be estimated. The 2008/2009 CCHS survey will be used for validation (approximately 4600 males and 6300 females). Overall calibration and discrimination will be assessed as well as calibration within predefined subgroups of importance to clinicians and policy makers. Research ethics approval has been granted by the Ottawa Health Science Network Research Ethics Board. DemPoRT results will be submitted for publication in peer-review journals and presented at scientific meetings. The algorithm will be assessable online for both population and individual uses. ClinicalTrials.gov NCT03155815, pre-results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No

  9. Amyotrophic lateral sclerosis with dementia: case report Esclerose lateral amiotrófica com demência: relato de caso

    Directory of Open Access Journals (Sweden)

    PAULO ROBERTO DE BRITO-MARQUES

    1999-06-01

    Full Text Available A patient is described in whom a profound and rapidly progressive dementia occurred in association with clinical features of amyotrophic lateral sclerosis. A magnetic resonance imaging showed signs of frontal and especially left temporal atrophy. The pattern of dementia indicated impaired frontotemporal lobe functions, evidenced by reduced tracer uptake in the frontotemporal lobes on brain single photon emission computed tomography. Neuropathological examination in this patient revealed mild frontotemporal atrophy with spongiform changes and neuronal loss affecting mainly layers II and III of the frontotemporal cortices. There was atrophy of the hypoglossal nuclei. The spinal cord changes were consistent with motor neuron disease. The patient showed an irreversible and progressive course. A review of the relevant literature was made.Demência de evolução rápida e progressiva associada com esclerose lateral amiotrófica ocorreu em uma paciente de 68 anos. A ressonância magnética mostrou sinais de atrofia frontal e, principalmente, temporal bilateral mais acentuada à esquerda. A demência se caracterizou como de tipo fronto-temporal, como sugere por hipoperfusão moderada nos lobos fronto-temporais através da tomografia cerebral computadorizada por emissão de fóton simples. O exame neuropatológico revelou atrofia leve fronto-temporal com alterações esponjiformes e perda neuronal afetando principalmente as camadas II e III dos córtices fronto-temporais. Havia importante perda de neurônios em ambos os núcleos do hipoglosso. A medula espinhal mostrou alterações consistentes com doença do neurônio motor. O caso teve curso de quatro anos até o óbito.

  10. Perfis Diferenciais de Perda de Memória entre a Demência Frontotemporal e a do Tipo Alzheimer

    Directory of Open Access Journals (Sweden)

    Allegri Ricardo F.

    2001-01-01

    Full Text Available Os estados iniciais da demência tipo Alzheimer (DTA caracterizam-se classicamente por deterioração da memória enquanto que as mudanças de conduta e de personalidade aparecem nas etapas iniciais da demência frontotemporal (DFT. Entretanto, na prática clínica, o diagnóstico diferencial é difícil. O objetivo do presente trabalho foi estudar o rendimento da memória de pacientes com DTA (n= 20 e com DFT (n= 20 comparando-o com um grupo de controles (n = 20. Os pacientes, emparelhados por idade e escolaridade, foram avaliados com uma bateria neuropsicológica exaustiva. Para a avaliação da memória, examinou-se a "queixa subjetiva" de perda de memória (memória subjetiva, a aprendizagem de uma lista de palavras (memória episódica e o desempenho no teste de denominação de Boston (memória semântica. As pontuações de ambos os grupos de pacientes, na grande maioria das provas, foram significativamente inferiores às dos controles. Os pacientes com DTA mostraram uma deterioração global da memória episódica (tipo amnésia e semântica com um alto nível de queixa subjetiva. Os sujeitos com DFT, por outro lado, apresentaram um déficit de memória importante na recuperação da informação, mas com melhores capacidades de registro da informação, apesar das dificuldades de reconhecimento do seu distúrbio.

  11. Prevalência de demência em diversas regiões do mundo: Análise dos estudos epidemiológicos de 1994 a 2000

    Directory of Open Access Journals (Sweden)

    Lopes Marcos A.

    2002-01-01

    Full Text Available OBJETIVO: Analisar os estudos de prevalência de demência, no período de 1994 a 2000. MÉTODOS: Foram utilizadas as bases de dados Medline e Lilacs e os seguintes critérios de inclusão: constituir artigo original, estimar prevalência de demência e utilizar amostra comunitária. RESULTADOS: Foram avaliados 38 artigos, originários de todos os continentes. A idade exerceu importante influência sobre os resultados, com taxas médias de prevalência de demência que variaram de 1,17% na faixa de 65-69 anos, a 54,83% na faixa acima de 95 anos. Houve predomínio do sexo feminino em 75% dos estudos avaliados. A relação doença de Alzheimer/demência vascular foi maior na América do Sul e menor na Ásia. DISCUSSÃO: Ocorreram avanços metodológicos, sobretudo com relação à maior homogeneidade dos critérios diagnósticos. O efeito da idade sobre o aumento das taxas de prevalência foi pronunciado, principalmente até os 90 anos de idade.

  12. Bio-Lebensmittel in der öffentlichen Gemeinschaftsverpflegung - Eine Studie auf dem dänischen Markt und in den entsprechenden Aufsichtsbehörden

    DEFF Research Database (Denmark)

    Nielsen, Thorkild; Kristensen, Niels Heine; Mikkelsen, Bent Egberg

    2003-01-01

    Nielsen T, Kristensen NH, Mikkelsen BE (2003): Bio-Lebensmittel in der öffentlichen Gemeinschaftsverpflegung - Eine Studie auf dem dänischen Markt und in den entsprechenden Aufsichtsbehörden. Proceedings from "Ökologischer Landbau der Zukunft - Die 7. Wissenschaftstagung zum Ökologischen Landbau...

  13. 25 Jahre - Institut fuer Geodaesie, Teil 3: Aus dem Leben des Instituts (25 Years - Institute of Geodesy, Part 3: The Life of the Institute)

    Science.gov (United States)

    2000-01-01

    1992 kaufmAinnischer Angestellter bei Roth- Electric * seit 1992 Abteilungsleiter Vernessung bei der Kreisverwaltung Neuruppin 36 Die Mitarbeiter des... engen Gassen zog. Splater verlagerten sich die Wege mehr und mehr in die Vogesen hinein bis hin zurn Hartmannsweiler Kopf und Grand Ballon, dem h6ch

  14. The 10 m-resolution TINITALY DEM as a trans-disciplinary basis for the analysis of the Italian territory: Current trends and new perspectives

    Science.gov (United States)

    Tarquini, Simone; Nannipieri, Luca

    2017-03-01

    The increasing availability of high resolution digital elevation models (DEMs) is changing our viewpoint towards Earth surface landforms. Nevertheless, large-coverage, intermediate-resolution DEMs are still largely used, and can be the ideal choice in several applications based on the processing of spatially-integrated information. In 2012 the Istituto Nazionale di Geofisica e Vulcanologia opened a website for the free download of the "TINTALY" Digital Elevation Model (DEM), which covers the whole Italian territory. Since then, about 700 users from 28 different countries have been accredited for data download, and a report of 4 years of data dissemination and use is presented. The analysis of the intended use reveals that the 10 m-resolution, seamless TINITALY DEM is of use for an extremely assorted research community. Accredited users are working in virtually any branch of the Earth Sciences (e.g. Volcanology, Seismology, and Geomorphology), in spatially integrated humanities (e.g. History and Archaeology), and in other thematic areas such as in applied Physics and Zoology. Many users are also working in local administrations (e.g. Regions and Municipalities) for civil protection or land use planning purposes. In summary, the documented activity shows that the dissemination of seamless, large coverage elevation datasets can fertilize the technological progress of the whole society providing a significant benefit to stakeholders.

  15. Effects of DEM source and resolution on WEPP hydrologic and erosion simulation: A case study of two forest watersheds in northern Idaho

    Science.gov (United States)

    J. X. Zhang; J. Q. Wu; K. Chang; W. J. Elliot; S. Dun

    2009-01-01

    The recent modification of the Water Erosion Prediction Project (WEPP) model has improved its applicability to hydrology and erosion modeling in forest watersheds. To generate reliable topographic and hydrologic inputs for the WEPP model, carefully selecting digital elevation models (DEMs) with appropriate resolution and accuracy is essential because topography is a...

  16. Large-baseline InSAR for precise topographic mapping: a framework for TanDEM-X large-baseline data

    Directory of Open Access Journals (Sweden)

    M. Pinheiro

    2017-09-01

    Full Text Available The global Digital Elevation Model (DEM resulting from the TanDEM-X mission provides information about the world topography with outstanding precision. In fact, performance analysis carried out with the already available data have shown that the global product is well within the requirements of 10 m absolute vertical accuracy and 2 m relative vertical accuracy for flat to moderate terrain. The mission's science phase took place from October 2014 to December 2015. During this phase, bistatic acquisitions with across-track separation between the two satellites up to 3.6 km at the equator were commanded. Since the relative vertical accuracy of InSAR derived elevation models is, in principle, inversely proportional to the system baseline, the TanDEM-X science phase opened the doors for the generation of elevation models with improved quality with respect to the standard product. However, the interferometric processing of the large-baseline data is troublesome due to the increased volume decorrelation and very high frequency of the phase variations. Hence, in order to fully profit from the increased baseline, sophisticated algorithms for the interferometric processing, and, in particular, for the phase unwrapping have to be considered. This paper proposes a novel dual-baseline region-growing framework for the phase unwrapping of the large-baseline interferograms. Results from two experiments with data from the TanDEM-X science phase are discussed, corroborating the expected increased level of detail of the large-baseline DEMs.

  17. SPH-DEM approach to numerically simulate the deformation of three-dimensional RBCs in non-uniform capillaries.

    Science.gov (United States)

    Polwaththe-Gallage, Hasitha-Nayanajith; Saha, Suvash C; Sauret, Emilie; Flower, Robert; Senadeera, Wijitha; Gu, YuanTong

    2016-12-28

    Blood continuously flows through the blood vessels in the human body. When blood flows through the smallest blood vessels, red blood cells (RBCs) in the blood exhibit various types of motion and deformed shapes. Computational modelling techniques can be used to successfully predict the behaviour of the RBCs in capillaries. In this study, we report the application of a meshfree particle approach to model and predict the motion and deformation of three-dimensional RBCs in capillaries. An elastic spring network based on the discrete element method (DEM) is employed to model the three-dimensional RBC membrane. The haemoglobin in the RBC and the plasma in the blood are modelled as smoothed particle hydrodynamics (SPH) particles. For validation purposes, the behaviour of a single RBC in a simple shear flow is examined and compared against experimental results. Then simulations are carried out to predict the behaviour of RBCs in a capillary; (i) the motion of five identical RBCs in a uniform capillary, (ii) the motion of five identical RBCs with different bending stiffness (K b ) values in a stenosed capillary, (iii) the motion of three RBCs in a narrow capillary. Finally five identical RBCs are employed to determine the critical diameter of a stenosed capillary. Validation results showed a good agreement with less than 10% difference. From the above simulations, the following results are obtained; (i) RBCs exhibit different deformation behaviours due to the hydrodynamic interaction between them. (ii) Asymmetrical deformation behaviours of the RBCs are clearly observed when the bending stiffness (K b ) of the RBCs is changed. (iii) The model predicts the ability of the RBCs to squeeze through smaller blood vessels. Finally, from the simulations, the critical diameter of the stenosed section to stop the motion of blood flow is predicted. A three-dimensional spring network model based on DEM in combination with the SPH method is successfully used to model the motion and

  18. Analysis of landslide development using aerial photographs and DEMs comparison, along part of the Chacoura River valley, Quebec, Canada.

    Science.gov (United States)

    Lévy, S.; Locat, J.; Jaboyedoff, M.; Demers, D.; Loye, A.

    2009-04-01

    The large plains of Eastern Canada sensitive clays are cut by numerous rivers, in a way that their slopes have been and are still affected by landslides. They play an important role in the modelling of the landscape of these regions. Hence, the role of erosion as a trigger of landslides is important. On the Chacoura River, north of Louiseville (Quebec), several large landslides scars, more or less recent, are visible. A first inventory of areas of erosion, slides and landslides clay was carried out by Locat et al. (1984) on some series of aerial photographs covering a period from 1948 to 1979. This study is based on a detailed analysis of aerial photographs, dating from 1948 to 1997 and an airborne LiDAR digital elevation model (DEM-LiDAR), dating from 2007, in a GIS environment, using two different approaches: (1) a map of the phenomena was drawn by identifying various elements such as land movements, limits of the slope, position of the river, the area covered by forest and agricultural drainage structures, e.g., and (2) the comparison of DEMs was performed to estimate slipped and eroded volumes, the rate of erosion on a section of the river (about 6 km) and the spatial distribution of movements. The results show that the location of landslides is directly linked to the presence of some characteristic topographical features, such as (1) the shape of the meandering river, (2) the flow of agricultural drainage, or (3) the erosion at the toe of the slope. Finally, the study of landslides over a period of 60 years shows that the major landslide scars in this area could be in fact the sum of several events of lesser importance. For example, a large landslide (around 13'000 m2) occurred in 1976 at the same place where a first landslide of 1500 m2 in 1964. Locat, J., Demers, D., Lebuis, J. and Rissmann, P. (1984), Prédiction des Glissements de Terrain; Application aux Argiles Sensibles, Rivière Chacoura, Québec, Canada, the IV International Symposium on Landslides

  19. Efficacy of pharmacological treatment of dementia Eficácia do tratamento farmacológico da demência

    Directory of Open Access Journals (Sweden)

    Leon Flicker

    2002-04-01

    Full Text Available Over the last 25 years an increasing number of studies have been performed to evaluate therapeutic agents for people with dementia. Although numerous agents have been trialed at this stage there little evidence that therapeutic agents can prevent dementia or ameliorate the progression of dementia of any type. There is some evidence that specific medical management in high risk individuals can prevent strokes, and thus probably prevent vascular dementia, although this is extrapolating from the available evidence. There is considerable evidence that cholinesterase inhibitor are effective for cognitive symptoms in people with mild to moderate AD, and there is some evidence that they are also effective for other behavioural and functional symptoms. The currently available cholinesterase inhibitors seem to have approximately the same sized effect and thus the choice of agent may be largely determined by the incidence of side-effects. These agents have modest effects and a cautious therapeutic trial is indicated for those subjects with mild to moderate AD.Durante os últimos 25 anos, um número crescente de ensaios clínicos vem sendo conduzido com objetivo de avaliar a eficácia terapêutica de drogas para o tratamento de indivíduos com demência. Embora várias medicações tenham sido testadas, até o momento há pouca evidência de que essas drogas possam prevenir a síndrome demencial ou interferir em sua progressão, qualquer que seja a etiologia. Há alguma evidência de que intervenções específicas podem reduzir o risco de acidente vascular cerebral em indivíduos com alto risco e, assim, prevenir o desenvolvimento de demência vascular – embora isto seja uma extrapolação feita a partir dos dados disponíveis. Há evidência relativamente robusta de que os inibidores da colinesterase são eficazes para o tratamento dos sintomas cognitivos de pessoas com doença de Alzheimer (DA de gravidade leve à moderada, e há alguma evidência de

  20. Evaluation of DEM-DISC, customized e-advice on health and social support services for informal carers and case managers of people with dementia; a cluster randomized trial.

    Science.gov (United States)

    Van Mierlo, Lisa D; Meiland, Franka J M; Van de Ven, Peter M; Van Hout, Hein P J; Dröes, Rose-Marie

    2015-08-01

    Few personalized e-interventions are available for informal and professional caregivers of people with dementia. The DEMentia Digital Interactive Social Chart (DEM-DISC) is an ICT tool to support customized disease management in dementia. The aim of this study was to improve and evaluate DEM-DISC, its user-friendliness and usefulness and to investigate the future implementation. A cluster randomized controlled trial (RCT) design was used with measurements at baseline, 6 and 12 months. A total of 73 informal caregivers of people with dementia, supported by 19 randomized case managers participated in the study. In the intervention group, both carers (n = 41) and case managers (n = 13) could access DEM-DISC during twelve months. The control group, 32 carers and 14 case managers, had no access to DEM-DISC. Semi-structured interviews were conducted with ten stakeholders. Informal caregivers who used DEM-DISC for twelve months reported an increased sense of competence than controls. A subgroup of users who frequently accessed DEM-DISC reported more met needs after six months than controls. Overall informal caregivers and case managers judged DEM-DISC as easy to learn and user-friendly. This study demonstrates that using DEM-DISC had a positive effect on the sense of competence and experienced (met) needs of informal carers. This shows the importance of user-friendly ICT solutions to assist carers in finding appropriate care services tailored to their specific situation and needs. For further implementation of DEM-DISC methods to keep the information updated is of great importance.

  1. Empirical relationships among triangular facet slope, facet height and slip rates along active normal faults from ASTER DEM data

    Science.gov (United States)

    Tsimi, Christina; Ganas, Athanassios

    2015-04-01

    ASTER DEM data (30-m pixel size) are used to derive empirical relationships between triangular facet attributes and slip rates along active normal faults. We sampled 232 triangular facets along 10 normal faults in Greece and Bulgaria that slip with rates from 0.1 mm/yr up to 1.3 mm/yr. The studied normal faults accumulate Quaternary tectonic strain in well-known extensional provinces, such as central Greece, Crete and SW Bulgaria. The normal fault footwalls analysed herein have been developed under similar long-term climatic conditions. It is suggested that two key geometrical features of the youngest generation of triangular facets (slope angle and height) can provide useful metrics to assess rates of deformation when seismological and geodetic data are lacking or not found in sufficient quantity to make reasonable assessments. Our derived empirical relation between slip rate and facet slope angle is: Y=0.057•X-1 where Y is fault slip rate (mm/yr) and X is facet slope angle (degrees), with an R² = 0.728. It is envisaged that our analysis may be helpful in assessing seismic hazard along normal faults with similar facet characteristics in other extensional settings. Note: This research was funded by The Rapid Analysis and Spatialisation Of Risk (RASOR) project http://www.rasor-project.eu/

  2. Towards a Discrete Element Method (DEM) for modeling anisotropic, nano- and colloidal scale particles in Molecular Dynamics (MD)

    Science.gov (United States)

    Marson, Ryan; Spellings, Matthew; Anderson, Joshua; Glotzer, Sharon

    2014-03-01

    Faceted shapes, such as polyhedra, are commonly created in experimental systems of nanoscale, colloidal, and granular particles. Many interesting physical phenomena, like crystalline nucleation and growth, vacancy motion, and glassy dynamics, are challenging to model in these systems because they require detailed dynamical information at the individual particle level. Within the granular materials community the Discrete Element Method has been used extensively to model systems of anisotropic particles under gravity, with friction. We report the first implementation of DEM MD intended for thermodynamic nanoscale simulation. Our method is implemented in parallel on the GPU within the HOOMD-Blue framework. By decomposing the force calculation into its components, this implementation can take advantage of massive data parallelism, enabling optimal use of the GPU for even relatively small systems while achieving a speedup of 60 times over a single CPU core. This method is a natural extension of classical molecular dynamics into the realm of faceted particles, and allows simulation of disparate size scales ranging from the nanoscale to granular particulates, all within the same framework.

  3. DEM analyses of the whole failure process of shallow foundation in plate load test on dense sand

    Science.gov (United States)

    Li, L.; Jiang, M. J.; Li, T.; Chen, S. L.

    2015-09-01

    Shallow foundations are widely used in civil engineering practice, but the instability mechanism is still unclear yet. Previously, the Finite Element Method (FEM) was commonly used to analyze the failure process of shallow foundations, but it meets difficulty in properly simulating the whole failure process of shallow foundation on the strain-softening material. Hence, the Discrete Element Method (DEM) is employed in this paper to study the instability mechanism of the shallow foundation via numerical plate load test with focus on the microscopic features evolution during vertical loading. In the simulation, an amplified gravity was applied to a dense granular ground to reproduce a gravity stress state at a large scale. Then, a plate was put on the granular ground to simulate the plate load test. Deformation pattern, particle velocity and distribution of void ratio in the ground were examined to illustrate the microscopic features in the whole failure process of the granular ground. The results show that: 1) There are a marked peak value and a settlement softening branch in the stress-settlement relationship. 2) The grids close to the edge of the plate are peculiarly extended and twisted. 3) Four particle motion patterns were observed in the velocity fields and the percentage of each motion pattern changes during loading. 4) The void ratio field varies during loading, and the distinguishing interface tends to be similar to Terzaghi's shear failure surface.

  4. Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow.

    Science.gov (United States)

    Carlos Varas, Álvaro E; Peters, E A J F; Kuipers, J A M

    2017-05-17

    We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas-solid contact efficiencies. Cluster gas-solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors.

  5. Optimization of operating conditions in a high-shear mixer using dem model: determination of optimal fill level.

    Science.gov (United States)

    Terashita, Keijiro; Nishimura, Takehiko; Natsuyama, Susumu

    2002-12-01

    For the purpose of evaluating optimal fill level of starting materials in a high-shear mixer, discrete element method (DEM) simulation was conducted to visualize kinetic status between particles. The simulation results obtained by changing fill levels were used to determine solid fraction of particles, particle velocity, particle velocity vector, and kinetic energy and discuss the flow pattern. Optimal fill level was obtained from the information on these matters. It was pointed out that understanding the kinetic energy between particles in an agitating vessel was effective in determining the optimal fill level. Granulation experiment was conducted to validate the optimal fill level obtained by the simulation, confirming the good agreement between these two results. It was pointed out that determination of kinetic energy between particles through the simulation was effective in obtaining an index of the kinetic status of particles. Further, it was confirmed that the simulation could provide more information than conventional granulation experiments could provide and also helpful in optimizing the operating conditions.

  6. Numerical Simulation of the Gas-Solid Flow by DEM-CFD Approach with Application to a Spouted Bed

    Directory of Open Access Journals (Sweden)

    Jinhe FAN

    2014-02-01

    Full Text Available The paper presents a computational study of the gas-solid flow in a three- dimensional spouted bed by a combined approach of discrete element method and computational fluid dynamics (DEM-CFD.The coupling between the discrete particle and continuum gas was achieved by applying the principle of Newton’s third law of motion. As a result, it is found that the motion of particles was forming a distinct circulation between center zone and boundary zone of the 3D spouted bed in macro, and there was a stagnant zone near the bottom of the bed in which the particle velocity is almost zero near the wall, they do not move anywhere. Pressure drop will be affected by wind speed and particle density. With enhancing of wind velocity, pressure drop appears an increasing trend until it is up to a certain value, and then the curve will have a certain degree of back and keep in an extension; Adding particle density, pressure drop and its swing is increased markedly. The results of this study provide important information in the spouted bed and may be helpful for better application and modification of this type of spouted bed to the industrial process.

  7. Effect of the characteristics of granular media on dynamic penetration test - Numerical study using 2D - DEM

    Science.gov (United States)

    Tran, Quoc Anh; Chevalier, Bastien; Breul, Pierre

    2017-06-01

    The paper presents a numerical study on the influence of the properties of granular media on light dynamic penetration test results. A numerical model based on the Discrete Element Method (DEM) in 2 dimensions has been carried out. The model is able to reproduce the penetration tests in dynamic conditions. The model provide for each impact, the load-penetration curve that presents the evolution of reaction forces of granular media acting on the tip of the penetration test. The load - penetration curves are investigated in terms of tip resistance and analyzed by using the Discrete Fourier Transform in order to study the oscillations of the curves. The influence of the properties of granular media on the load-penetration curve has been investigated. We concentrated on the influence of particle friction and sample compacity. Besides the known results obtained in the literature by the dynamic tip resistance analysis for macroscopic response, we found that for a particle friction greater than 0.5, tip resistance and oscillations of signal are stable. Concerning the sample compacity, although variation of volume fraction is tight (ϕ = 0.817 - 0.844), a clear variation in terms of tip resistance and amplitude spectrum is highlighted.

  8. Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

    Science.gov (United States)

    2017-01-01

    We report a computational fluid dynamics–discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas–solid contact efficiencies. Cluster gas–solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors. PMID:28553011

  9. Revelation of the interactions between bedload and turbulent flow in open channels using a LES-DEM coupled model

    Science.gov (United States)

    Liu, X.; Liu, D.; Fu, X.

    2015-12-01

    Bedload transport is an important transport mode for sediment, which has great influence on the erosion and deposition near channel bed. To fully understand the mechanism of bedload transport, it is critical to know the motion characteristics and the interaction between bedload particles and turbulent structures. However, the motion of bedload particles can rarely be measured accurately because of experimental difficulties. In this work, a model of bedload transport in open channel flows is built by combining large eddy simulation (LES) with discrete element model (DEM) using a momentum coupling method. For the particles, a four-way coupling approach is utilized. Numerical experiments are conducted and post processed by statistic and quadrant threshold analysis. The characteristics of the kinematics and dynamics of the bedload particles are of particular interest during the analysis. The particle trajectory, velocity distribution and force condition are processed for further analysis. The model is validated by flow field and bedload transport rate data. The model produces an exponential form of the velocity statistics, which have been confirmed by experiments in the literature. The quadrant analysis also reveals rich information about the interaction between the particle and the flow. Among many things, it is found that the ejection events are influenced more than the sweep event. It is because the sweep event is more controlled by the outer flow. The size of the near wall coherent structure is smaller and their occurrence is less frequent when the particles are in motion.

  10. Simulation of a Magneto-Rheological Fluid Based, Jamming, Soft Gripper Using the Soft Sphere DEM in LIGGGHTS

    Science.gov (United States)

    Leps, Thomas; Hartzell, Christine; Wereley, Norman; Choi, Young

    2017-11-01

    Jamming soft grippers are excellent universal grippers due to their low dependence on the shape of objects to be grabbed, and low stiffness, mitigating the need for object shape data and expensive force control of a stiff system. These grippers now rely on jamming transitions of dry grains under atmospheric pressure to hold objects. In order to expand their use to space environments, a gripper using magnetic actuation of a magneto-rheological fluid (MR Gripper) is being developed. The MR fluid is a suspension of μm scale iron grains in a silicone oil. When un-magnetized the fluid behaves as a dense suspension with low Bagnold number. When magnetized, it behaves like a jammed granular material, with magnetic forces between the grains dominating. We are simulating the gripper using LIGGGHTS, an open-source soft sphere DEM code. We have modeled both the deformable gripper membrane and the MR fluid itself using the LIGGGHTS framework. To our knowledge, this is the first time that the induced magnetic dipoles required to accurately simulate the jamming behavior of MR fluids have been modeled in LIGGGHTS. This simulation allows the rapid optimization of the hardware and magnetic field geometries, as well as the fluid behavior, without time consuming, and costly prototype revisions.

  11. Das Ehlers-Danlos-Syndrom mit Schwerpunkt auf dem hypermobilen Typ und dessen Begleiterkrankungen - eine Literaturübersicht

    Directory of Open Access Journals (Sweden)

    Sturm KU

    2016-01-01

    Full Text Available Das Ehlers-Danlos-Syndrom (EDS beschreibt eine Gruppe seltener, hereditärer, multisystemischer Bindegewebserkrankungen, die Gelenke, Sehnen, Muskeln, Organe, Haut und Gefäße betreffen können. Durch die Vielfalt der Symptome und die unterschiedliche Krankheitsausprägung, selbst bei gleichem EDS-Typ, ist die Diagnostik deutlich erschwert. Derzeit differenziert man laut Villefranche-Nosologie 6 Haupttypen und einige sehr seltene Typen, die sich durch ihre genetischen Ursachen und Verlaufsformen unterscheiden. Der am häufigsten vorkommende Typ ist der hypermobile Typ, welcher gleichzeitig auch gehäuft in Kombination mit anderen Erkrankungen wie dem posturalen orthostatischen Tachykardiesyndrom (POTS, Mastzellaktivierungssyndrom (MCAS, Osteoporose, Polyneuropathie, Myopathie, Mitralklappeninsuffizienz, Blutungsneigung und vielen anderen Begleiterkrankungen vorkommt. Gerade aufgrund dieser Komorbiditäten ist die Behandlung des EDS ex trem schwierig und stellt die verschiedensten Fachärzte vor große Herausforderungen. Die Therapie beschränkt sich auf eine symptomatische Stufentherapie aus konservativer physikalischer Therapie, einer medikamentösen Schmerztherapie und als letzte Instanz einer operativen Intervention. Die Krankheitsausprägung kann von leichter Hypermobilität bis zu schwerer körperlicher Behinderung reichen.

  12. Integrated Optical and SAR Imagery with DEM to Quantify Glacier Water Storage Change in Upper Mekong River Basin

    Science.gov (United States)

    Liu, G. T.; Chen, J. B.; Le, T. S.; Chang, C. P.; Shum, C. K.; Tseng, K. H.

    2015-12-01

    In the past few decades, regional increase in air temperature has accelerated the ice melting in polar, sub-polar, and major land glacial areas. The glaciers in Tibetan Plateau, the largest glaciers outside Polar Regions and the sources of several trans-boundary major rivers, are now showing aggravated terminus retreat and thinning. The variation of freshwater availability is crucial for the economic development in Mainland Southeast Asia, especially in hydroelectric generation and agriculture irrigation. These rives, including the Mekong River, is also subject to upstream-downstream conflict and transboundary issues. In this study, we propose to estimate the remaining glacier water storage in Mekong River basin, and further analyze the impact of glacier retreat on these dams/reservoirs for the next decade. By calculating the Modified Normalized Difference Water Index (MNDWI), the water surface area (WSA) can thus be extracted from optical satellite images. On the other hand, the ice surface area (ISA) can be derived from the Polarimetric Synthetic Aperture Radar (POLSAR) images. With different polarization states of electromagnetic wave reflected by earth surface, POLSAR image can effectively identify glacier/ice from snow. Combined WSA and ISA information with digital elevation model (DEM), the change of freshwater storage in glaciers can be estimated. In the end, the influence on dams/reservoirs in the Mekong River caused by glacier retreat can be forecasted. The result can also be applied to hydrology, water allocation, and economy/agriculture policy determination.

  13. DEM Study of Wet Cohesive Particles in the Presence of Liquid Bridges in a Gas Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Yurong He

    2014-01-01

    Full Text Available A modified discrete element method (DEM was constructed by compositing an additional liquid-bridge module into the traditional soft-sphere interaction model. Simulations of particles with and without liquid bridges are conducted in a bubbling fluidized bed. The geometry of the simulated bed is the same as the one in Müller’s experiment (Müller et al., 2008. A comparison between the dry and the wet particular systems is carried out on the bubble behavior, the bed fluctuation, and the mixing process. The bubble in the dry system possesses a regular round shape and falling of scattered particles exists while the bubble boundary of the wet particles becomes rough with branches of agglomerates stretching into it. The mixing of the dry system is quicker than that of the wet system. Several interparticle liquid contents are applied in this work to find their influence on the kinetic characteristic of the wet particle flow. With an increase of liquid content, the mixing process costs more time to be completed. Symmetrical profiles of the velocity and granular temperature are found for two low liquid contents (0.001% and 0.01%, while it is antisymmetrical for the highest liquid content (0.1%.

  14. Coupled hydro-thermo-mechanical modeling of hydraulic fracturing in quasi-brittle rocks using BPM-DEM

    Directory of Open Access Journals (Sweden)

    Ingrid Tomac

    2017-02-01

    Full Text Available This paper presents an improved understanding of coupled hydro-thermo-mechanical (HTM hydraulic fracturing of quasi-brittle rock using the bonded particle model (BPM within the discrete element method (DEM. BPM has been recently extended by the authors to account for coupled convective–conductive heat flow and transport, and to enable full hydro-thermal fluid–solid coupled modeling. The application of the work is on enhanced geothermal systems (EGSs, and hydraulic fracturing of hot dry rock (HDR is studied in terms of the impact of temperature difference between rock and a flowing fracturing fluid. Micro-mechanical investigation of temperature and fracturing fluid effects on hydraulic fracturing damage in rocks is presented. It was found that fracture is shorter with pronounced secondary microcracking along the main fracture for the case when the convective–conductive thermal heat exchange is considered. First, the convection heat exchange during low-viscosity fluid infiltration in permeable rock around the wellbore causes significant rock cooling, where a finger-like fluid infiltration was observed. Second, fluid infiltration inhibits pressure rise during pumping and delays fracture initiation and propagation. Additionally, thermal damage occurs in the whole area around the wellbore due to rock cooling and cold fluid infiltration. The size of a damaged area around the wellbore increases with decreasing fluid dynamic viscosity. Fluid and rock compressibility ratio was found to have significant effect on the fracture propagation velocity.

  15. EU Kids Online – Der sichere Umgang mit dem Internet. Österreich im europäischen Vergleich

    Directory of Open Access Journals (Sweden)

    Ingrid Paus-Hasebrink

    2009-09-01

    Full Text Available Die Ergebnisse des dreijährigen europäischen Forschungsprojektes „EU Kids Online I“ zu Erfahrungen von Kindern und Jugendlichen mit dem Internet in Europa zeigen, dass die Forschungslage zu dieser Thematik in Österreich – aber auch in vielen anderen Ländern – als defizitär bezeichnet werden muss. Zudem zählt Österreich bei mittlerer Nutzungshäufigkeit des Internets zu den Ländern mit immerhin mittlerem Online-Risiko. Österreichische Eltern scheinen sich der mit der Internetnutzung ihrer Kinder verbundenen Gefahren noch recht wenig bewusst zu sein. Im Nachfolgeprojekt "EU Kids Online II" steht nun der Bereich der Online-Risiken im Mittelpunkt einer europaweiten Befragung. The results of the triennial European research project "EU Kids Online I", which focused on online-experiences of children and teenagers in Europe, show, that the relevant state of research in Austria as well as in many other European countries is insufficient. Moreover, Austria belongs to the group with medium use of the internet and medium online risk. All in all, Austrian parents seem to be less aware of the risks children are encountering online. In the follow-up project "EU Kids Online II" online risks are the main topic of a pan-European survey.

  16. Entwicklung und lmplementierung von Analysemethoden zum Erfassen vonGeschwindigkeitsfeldem mit dem PIV Verfahren (Development and Implementation of Analytical Methods for Detecting Velocity Fields using PIV- Method)

    Science.gov (United States)

    2016-04-26

    FUNDING NUMBERS Entwicklung und lmplementierung von Analysemethoden zum Erfassen von Geschwindigkeitsfeldem mit dem PIY-Yerfahren (Development and...thesis presents two new analysis methods for the measurement of flow fields using Particle -Image-Yelocimetry (PlY). PlY gives the opportunity of...two photograph ies of the patiicles are taken within a short period of time. In today’s evaluation the translationally shift of the particles is

  17. Gully incision rates on the bedrock of a large dip-slope landslide revealed by multi-period LiDAR DEMs

    Science.gov (United States)

    Chan, Y. C.; Hsieh, Y. C.

    2017-12-01

    Recent advances in airborne laser scanning (ALS) technology have provided a great opportunity for characterizing surface erosion through developing improved methods in multi-period DEM differencing and geomorphometry. This study uses three periods of ALS digital elevation model (DEM) data to analyze the short-term erosional features of the Tsaoling landslide triggered by the 1999 Chi-Chi earthquake in Taiwan. Two methods for calculating the bedrock incision rate, the equal-interval cross section selection method and the continuous swath profiles selection method, were used in the study after nearly ten years of gully incision following the earthquake-triggered dip-slope landslide. Multi-temporal gully incision rates were obtained using the continuous swath profiles selection method, which is considered a practical and convenient approach in terrain change studies. After error estimation and comparison of the multi-period ALS DEMs, the terrain change in different periods can be directly calculated, reducing time-consuming fieldwork such as installation of erosion pins and measurement of topographic cross sections on site. In this study, the gully bedrock incision rates ranged between 0.23 and 3.98 m/year, remarkably higher than the typical results from the previous studies. By comparing the DEM data, aerial photos, and precipitation records of this area, the effects of erosion could be observed from the retreat of the Chunqiu Cliff outline during August 2011 to September 2012. It was inferred that the change in the topographic elevation during 2011-2012 was mainly due to the torrential rain brought by Typhoon Soula, which occurred on 30 July 2012. The local gully incision rate in the lower part of the landslide surface was remarkably faster than that of the other regions, suggesting that the fast incision of the toe area possibly contributes to the occurrence of repeated landslides in the Tsaoling area.

  18. [Robert Schweitzer. Eine Unveröffentlichte Quelle zur Schulgeschichte von Reval Ferdinand Wiedemanns Geschichte des Revaler Gouvernementsgymnasiums aus dem Jahr 1856] / Paul Kaegbein

    Index Scriptorium Estoniae

    Kaegbein, Paul

    2008-01-01

    Arvustus: Robert Schweitzer. Eine Unveröffentlichte Quelle zur Schulgeschichte von Reval Ferdinand Wiedemanns Geschichte des Revaler Gouvernementsgymnasiums aus dem Jahr 1856. - Buch und Bildung im Baltikum. Münster : LIT, 2005. lk. 495-525. Kubermangugümnaasiumi vanemõpetaja Ferdinand Wiedemann kirjutas 1856. aastal kooli ajaloo, mis mingitel põhjustel jäi avaldamata. Tema tööd on kasutanud 1881. aastal Gotthard von Hansen

  19. Lider fallen zu wie die Tore der Burg : [luuletused kogust "Simunapäev"] / Kristiina Ehin ; aus dem Estnischen von Gisbert Jänicke

    Index Scriptorium Estoniae

    Ehin, Kristiina, 1977-

    2004-01-01

    Sisu: die nachricht von der sanktgeorgsnacht = Jüriöö sõnum ; sie standen unter einem schiefen dach = nad seisid viltuse katuse all ; "der soldat steht auf dem hof ..." = "püssimees seisab õues..." ; "der mond heult..." = "kuu ulub..." ; der frauenräuber = naisteröövija ; "ich schlafe als schlamm im wald..." = "magan mudana metsas..." ; "ruhig erhebt sich der weihrauchdunst..." = "vaikselt tõuseb taevasse..."

  20. Therapeutische Effekte von Iloprost und dem PDE 3/4-Inhibitor Tolafentrin im Modell der Monocrotalin-induzierten chronischen pulmonalen Hypertonie der Ratte

    OpenAIRE

    Kreißelmeier, Klaus-Peter

    2010-01-01

    Die schwere pulmonale Hypertonie ist eine erheblich die Lebensqualität einschränkende Erkrankung mit einer hohen Mortalität. Wir untersuchten die therapeutischen Effekte von Iloprost, einem langwirksamen Prostazyklinanalogon, und dem dual-selektiven Phosphodiesterase 3/4-Inhibitor Tolafentrin während akuter Gabe sowie bei Dauertherapie in einem Tiermodell der Monocrotalin-induzierten pulmonalen Hypertonie der Ratte. Achtundzwanzig Tage nach Gabe des Alkaloids war der rechtsventrikuläre syste...

  1. Direct regional quasi-geoid determination using EGM2008 and DEM: A case study for Mainland China and its vicinity areas

    Directory of Open Access Journals (Sweden)

    Jin Li

    2015-11-01

    Full Text Available Earth's gravity model (EGM helps people better determine the figure of Earth, which is generally represented by a global geoid. For a considerable amount of practical applications, people use quasi-geoid to approximate the geoid, thus the quasi-geoid is also treated as an important height datum. In this study we revisit the method to directly determine regional quasi-geoid using EGM and digital elevation model (DEM, on the basis of Molodensky theory. According to the method we obtain a 5′ × 5′ quasi-geoid for Mainland China and its vicinity areas, based on the EGM2008 gravitational potential model and the Shuttle Radar Topography Mission (SRTM DEM model. By comparing height anomalies derived from EGM2008 with observations at 70 GPS/leveling points in areas including northwest, mid-west, mid-east and southeast of China, we find that the 5′ × 5′ EGM2008 quasi-geoid well fits the GPS/leveling results, with average deviations less than 10 cm for the selected areas in east China (with mainly plain topography and ∼20 cm for the selected areas in west China (highland or mountainous areas. We also discuss a few technical issues for directly determining height anomalies based on EGM and DEM, under the frame of Molodensky theory.

  2. Mechanical-biological waste conditioning with controlled venting - the Meisenheim mechanical-biological waste conditioning plant; Mechanisch-biologische Restabfallbehandlung nach dem Kaminzugverfahren - MBRA Meisenheim

    Energy Technology Data Exchange (ETDEWEB)

    Hangen, H.O. [Abfallwirtschaftsbetrieb Landkreis Bad Kreuznach, Bad Kreuznach (Germany)

    1998-12-31

    The decision of the rural district of Bad Kreuznach to propose creating facilities for mechanical-biological waste conditioning at the new northern Meisenheim landfill was consistent and correct. It will ensure that the material deposited at this new, state-of-the-art landfill is organically `lean` and can be deposited with a high density. Preliminary sifting of the material prior to depositing safeguards that no improper components are inadvertently included. Three years of operation warrant the statement that waste components that cannot be appropriately biologically conditioned should be eliminated prior to rotting. (orig.) [Deutsch] Die Entscheidung des Landkreises Bad Kreuznach, der neu eingerichteten Norddeponie Meisenheim eine MBRA vorzuschlaten, war auf jeden Fall konsequent und richtig. Es ist damit sicher gestellt, dass in diesem neuen nach dem Stand der Technik eingerichteten Deponiebereich von Anfang an ein Material eingelagert wird, das `organisch abgemagert` ist und mit hoher Einbaudichte eingebaut werden kann. Die Sichtung des gesamten Deponie-Inputs in der Vorsortierhalle gibt ein Stueck Sicherheit, dass keine nicht zugelassenen Stoffe verdeckt dem Ablagerungsbereich der Deponie zugefuehrt werden. Nach mehr als 3 Jahren Betriebszeit kann festgestellt werden, dass biologisch nicht sinnvoll behandelbare Abfallbestandteile vor dem Rotteprozess abgetrennt werden sollten. (orig.)

  3. Evaluation of Multiresolution Digital Elevation Model (DEM from Real-Time Kinematic GPS and Ancillary Data for Reservoir Storage Capacity Estimation

    Directory of Open Access Journals (Sweden)

    Yashon O. Ouma

    2016-04-01

    Full Text Available This study presents the estimation of reservoir storage capacity using multiresolution Real-Time Kinematic Global Positioning System (RTK-GPS DEM, in comparison with ASTER and contour-derived DEM. Through RMSE comparisons of the elevation point uncertainty and error analysis, the results shows that the RTK-GPS DEM gave the best results for the reservoir capacity-area power curve estimation, defined by a convex slope with an exponential deterministic relationship given by V = 0.09 × A 1.435 . The results further show the existence an empirical relationship between the reservoir volume certainty and the GPS point density d i as V e = c × d i ρ . This relationship is dependent on the reservoir terrain, slope and surface area. Validation of the results with in situ data showed the differences between the simulated and observed storage volumes was less than +10%, and using the Nash-Sutcliffe coefficient of efficiency on the storage volumes, an average efficiency of +0.7 on the monthly observed and simulated reservoir storage volume was observed.

  4. The geomorphological evidences of subsidence in the Nile Delta: Analysis of high resolution topographic DEM and multi-temporal satellite images

    Science.gov (United States)

    El Bastawesy, M.; Cherif, O. H.; Sultan, M.

    2017-12-01

    This paper investigates the relevance of landforms to the subsidence of the Nile Delta using a high resolution topographic digital elevation model (DEM) and sets of multi-temporal Landsat satellite images. 195 topographic map sheets produced in 1946 at 1:25,000 scale were digitized, and the DEM was interpolated. The undertaken processing techniques have distinguished all the natural low-lying closed depressions from the artificial errors induced by the interpolation of the DEM. The local subsidence of these depressions from their surroundings reaches a maximum depth of 2.5 m. The regional subsidence of the Nile Delta has developed inverted topography, where the tracts occupied by the contemporary distributary channels are standing at higher elevations than the areas in between. This inversion could be related to the differences in the hydrological and sedimentological properties of underlying sediments, as the channels are underlain by water-saturated sands while the successions of clay and silt on flood plains are prone to compaction. Furthermore, the analysis of remote sensing and topographic data clearly show significant changes in the land cover and land use, particularly in the northern lagoons and adjacent sabkhas, which are dominated by numerous low subsiding depressions. The areas covered by water logging and ponds are increasing on the expense of agricultural areas, and aquaculture have been practiced instead. The precise estimation of subsidence rates and distribution should be worked out to evaluate probable changes in land cover and land use.

  5. Direct Measurements of Bedrock Incision Rates on the Surface of a Large Dip-slope Landslide by Multi-Period Airborne Laser Scanning DEMs

    Directory of Open Access Journals (Sweden)

    Yu-Chung Hsieh

    2016-10-01

    Full Text Available This study uses three periods of airborne laser scanning (ALS digital elevation model (DEM data to analyze the short-term erosional features of the Tsaoling landslide triggered by the 1999 Chi-Chi earthquake in Taiwan. Two methods for calculating the bedrock incision rate, the equal-interval cross section selection method and the continuous swath profiles selection method, were used in the study after nearly ten years of gully incision following the earthquake-triggered dip-slope landslide. Multi-temporal gully incision rates were obtained using the continuous swath profiles selection method, which is considered a practical and convenient approach in terrain change studies. After error estimation and comparison of the multi-period ALS DEMs, the terrain change in different periods can be directly calculated, reducing time-consuming fieldwork such as installation of erosion pins and measurement of topographic cross sections on site. The gully bedrock incision rate calculated by the three periods of ALS DEMs on the surface of the Tsaoling landslide ranged from 0.23 m/year to 3.98 m/year. The local gully incision rate in the lower part of the landslide surface was found to be remarkably faster than that of the other regions, suggesting that the fast incision of the toe area possibly contributes to the occurrence of repeated landslides in the Tsaoling area.

  6. Contours, This Layer was derived from the USGS National Elevation Dataset (NED) based on 7.5 minute Digital Elevation Model (DEM) image files., Published in 1999, 1:24000 (1in=2000ft) scale, Atlanta Regional Commission.

    Data.gov (United States)

    NSGIC Regional | GIS Inventory — Contours dataset current as of 1999. This Layer was derived from the USGS National Elevation Dataset (NED) based on 7.5 minute Digital Elevation Model (DEM) image...

  7. Messung der Vorwärts-Rückwärts-Ladungsassymetrie von b-Quarks bei Energien nahe der Z0-Resonanz. Untersuchung von Ereignissen mit initialem b-Quark unter Verwendung der Jetladungstechnik mit dem DELPHI Detektor

    CERN Document Server

    Schwering, Britta

    Messung der Vorwärts-Rückwärts-Ladungsassymetrie von b-Quarks bei Energien nahe der Z0-Resonanz. Untersuchung von Ereignissen mit initialem b-Quark unter Verwendung der Jetladungstechnik mit dem DELPHI Detektor

  8. Estratégias comunicativas de cuidadores de idosos com demência: uma revisão sistemática

    Directory of Open Access Journals (Sweden)

    Lais Lopes Delfino

    2016-06-01

    Full Text Available RESUMO Objetivo Conduzir uma revisão sistemática de estudos que investigaram estratégias comunicativas utilizadas por cuidadores de idosos com demência, publicados entre 1995 e 2015. Métodos O levantamento de estudos foi feito usando as seguintes palavras-chave “comunicação e cuidador e demência” e “comunicação e cuidador e Alzheimer”, e os termos em inglês “elderspeak and dementia”, “caregiver’s talk and dementia”, “communication and caregiver and dementia” e “communicative and caregiver and Alzheimer”. Desta revisão sistemática, foram excluídos os artigos de intervenção e aqueles que não tinham descrito entre seus objetivos investigar estratégias comunicativas usadas por cuidadores de idosos com demência. Resultados Apenas 22 estudos preencheram os critérios de inclusão. Os estudos revisados mostraram que os cuidadores de idosos com demência utilizam estratégias comunicativas que são ineficazes (por exemplo, comunicação infantilizada; comunicação “controle” e complexa e eficazes (usar frases simples; dar um comando por vez; realizar perguntas em que a opção de resposta é sim ou não, entre outras. Conclusão É importante avaliar as percepções e avaliações dos cuidadores acerca da eficácia da estratégia utilizada, para que depois sejam ensinadas habilidades de comunicação para cuidadores familiares e cuidadores formais. A comunicação bem-sucedida deve promover a participação dos idosos com demência, contribuindo para manutenção da autonomia e participação tanto dos cuidadores quanto das pessoas acometidas por esse quadro.

  9. Lava emplacements at Shiveluch volcano (Kamchatka) from June 2011 to September 2014 observed by TanDEM-X SAR-Interferometry

    Science.gov (United States)

    Heck, Alexandra; Kubanek, Julia; Westerhaus, Malte; Gottschämmer, Ellen; Heck, Bernhard; Wenzel, Friedemann

    2016-04-01

    As part of the Ring of Fire, Shiveluch volcano is one of the largest and most active volcanoes on Kamchatka Peninsula. During the Holocene, only the southern part of the Shiveluch massive was active. Since the last Plinian eruption in 1964, the activity of Shiveluch is characterized by periods of dome growth and explosive eruptions. The recent active phase began in 1999 and continues until today. Due to the special conditions at active volcanoes, such as smoke development, danger of explosions or lava flows, as well as poor weather conditions and inaccessible area, it is difficult to observe the interaction between dome growth, dome destruction, and explosive eruptions in regular intervals. Consequently, a reconstruction of the eruption processes is hardly possible, though important for a better understanding of the eruption mechanism as well as for hazard forecast and risk assessment. A new approach is provided by the bistatic radar data acquired by the TanDEM-X satellite mission. This mission is composed of two nearly identical satellites, TerraSAR-X and TanDEM-X, flying in a close helix formation. On one hand, the radar signals penetrate clouds and partially vegetation and snow considering the average wavelength of about 3.1 cm. On the other hand, in comparison with conventional InSAR methods, the bistatic radar mode has the advantage that there are no difficulties due to temporal decorrelation. By interferometric evaluation of the simultaneously recorded SAR images, it is possible to calculate high-resolution digital elevation models (DEMs) of Shiveluch volcano and its surroundings. Furthermore, the short recurrence interval of 11 days allows to generate time series of DEMs, with which finally volumetric changes of the dome and of lava flows can be determined, as well as lava effusion rates. Here, this method is used at Shiveluch volcano based on data acquired between June 2011 and September 2014. Although Shiveluch has a fissured topography with steep slopes

  10. Melker Meilensteine auf dem Weg in ein naturwissenschaftliches Zeitalter - Glanzlichter der Ausstellung zum Internationalen Astronomiejahr 2009 in der Melker Stiftsbibliothek.

    Science.gov (United States)

    Beck, Paul G.; Zotti, Georg

    2009-06-01

    Das Mittelalter wird weithin als die dunkle Epoche in der Geschichte der Europäischen Wissenschaften betrachtet, und insbesondere das Leben in den Klöstern galt lange Zeit als frei von jeglichem Interesse für Naturwissenschaften abseits der Medizin. Im Mittelalter galt die Astronomie bloß als Mittel zum Zweck, um religiöse und zivile Kalender erstellen zu können. Durch den Bestand der Handschriftenkammer der Melker Stiftsbibliothek eröffnet sich uns eine neue Sichtweise auf das gegen Ende des Mittelalters wachsende Interesse an den Naturwissenschaften. Dies wurde durch die starke Aufwertung der Klosterbibliothek im Rahmen der 'Melker Reform' im 15. Jahrhundert noch weiter verstärkt. Diese Epoche fällt mit der Frühphase der Universität Wien und der 'ersten Wiener Schule der Astronomie' zusammen. Dieser Artikel beleuchtet ausgewählte astronomischen Werke in der Melker Stiftsbibliothek zwischen dem frühen 9 und dem 18. Jahrhundert. Einen Schwerpunkt stellt das Wirken der Wiener Schule der Astronomie dar, wobei wir u.a. die Melker Abschrift von Peuerbachs Gutachten über den Kometen von 1456 sowie die im Stift Melk durchgeführte Beobachtung der Mondfinsternis von 1457 durch Regiomontanus und Peuerbach beleuchten. Dieser Beitrag ist der einführende Übersichtsartikel zum Ausstellungsprojekt in der Melker Stiftsbibliothek im Rahmen des Internationalen Jahres der Astronomie 2009. The medieval period is commonly seen as a dark epoch for science in Europe. Especially monasteries were seen as institutions without interest in natural sciences except for medicine. Astronomy was allegedly only a tool to construct religious and civil calendars. The inventory of the medieval manuscript collection of the library of the Abbey of Melk allows a new view on the growing interest in the exact sciences towards the end of the medieval ages. This interest was intensified through the increased importance of the monastery library due to the monastery reform concept, created in

  11. Evaluation of short-term geomorphic changes in differently impacted gravel-bed rivers using improved dems of difference

    Directory of Open Access Journals (Sweden)

    F. Delai

    2013-09-01

    Full Text Available The evaluation of the morphological dynamics of rivers is increasingly focusing, in recent years, on the achievement of quantitative estimates of change in order to identify geomorphic trends and forecast targeted restoration actions. Thanks to the development of more effective and reliable survey technologies, more accurate Digital Elevation Models (DEM can be produced and, through their consequent differencing (DoD, extremely useful geomorphic analyses can be carried out. In this situation, a major role is played by uncertainty, especially in the final volumetric rates of erosion and deposition processes, that may lead to misinterpretation of spatial and temporal changes. This paper aims at achieving precise geomorphic estimates derived from subsequent hybrid (LiDAR and bathymetric points surface representations. The study areas consist of gravel-bed reaches of two differently impacted fluvial environments, Piave and Tagliamento rivers, that were affected by two severe flood events (Piave, R.I. of 7 and 10 years and Tagliamento, R.I. of 15 and 12 years in the inter-surveys period. The basic Hybrid Digital Elevation Models (HDTM were processed accounting for spatially variable uncertainty and considering, beside slope and point density input variables, a novel component measuring the quality of the bathymetric derived points. In fact, since the major changes occur within river channels, the integration of this variable evaluating the precision of the bathymetric channel elevations in the HDTMs, has allowed, through the creation of targeted FIS (Fuzzy Inference System rules, to obtain reliable geomorphic estimates of change. Volumes and erosion and deposition patterns were then analyzed and compared to outline the different dynamics among the sub-reaches and the two river systems.

  12. Modeling Change of Topographic Spatial Structures with DEM Resolution Using Semi-Variogram Analysis and Filter Bank

    Directory of Open Access Journals (Sweden)

    Chunmei Wang

    2016-06-01

    Full Text Available In this paper, the way topographic spatial information changes with resolution was investigated using semi-variograms and an Independent Structures Model (ISM to identify the mechanisms involved in changes of topographic parameters as resolution becomes coarser or finer. A typical Loess Hilly area in the Loess Plateau of China was taken as the study area. DEMs with resolutions of 2.5 m and 25 m were derived from topographic maps with map scales of 1:10,000 using ANUDEM software. The ISM, in which the semi-variogram was modeled as the sum of component semi-variograms, was used to model the measured semi-variogram of the elevation surface. Components were modeled using an analytic ISM model and corresponding landscape components identified using Kriging and filter bank analyses. The change in the spatial components as resolution became coarser was investigated by modeling upscaling as a low pass linear filter and applying a general result to obtain an analytic model for the scaling process in terms of semi-variance. This investigation demonstrated how topographic structures could be effectively characterised over varying scales using the ISM model for the semi-variogram. The loss of information in the short range components with resolution is a major driver for the observed change in derived topographic parameters such as slope. This paper has helped to quantify how information is distributed among scale components and how it is lost in natural terrain surfaces as resolution becomes coarser. It is a basis for further applications in the field of geomorphometry.

  13. Sick building syndrome - results of the 'Proklima' research project; Befindlichkeitsstoerungen in Buerogebaeuden - Ergebnisse aus dem Proklima Forschungsprojekt

    Energy Technology Data Exchange (ETDEWEB)

    Kruppa, B. [Bundesindustrieverband Heizungs-, Klima-, Sanitaertechnik und Technische Gebaeudesysteme e.V., Bonn (Germany); Bischof, W.; Brasche, S. [Arbeitsgruppe Raumklimatologie der FSU Jena (ARK), Erfurt (Germany); Bullinger-Naber, M. [Hamburg Univ. (Germany). Abt. fuer Medizinische Psychologie; Mayer, E. [Fraunhofer-Institut fuer Bauphysik, Holzkirchen (Germany); Gebhardt, H. [Wuppertal Univ. (Gesamthochschule) (Germany). Inst. fuer Arbeitsmedizin, Sicherheitstechnik und Ergonomie

    2000-07-01

    In the world's biggest research project, the sick building syndrome was investigated in Germany between 1995 and 1999. In all, 8 air-conditioned buildings and 6 non-air-conditioned buildings, 40 space HVAC systems and 1497 places of work were analyzed, and 4,500 persons were asked to provide data. For the first time ever, measured physical, biological and chemical data were compared with the subjective data provided by the inquiry forms. It was found that the concentrations and hygienic status of air conditioning systems do have an effect on subjective comfort. Buildings with well-designed and well-serviced space HVAC systems had better results than buildings without air conditioning systems. However, it is the psychosocial environment and the job description of building inhabitants that decide their response in terms of sick building syndrome. Factors like gender, job satisfaction, job specifications and educational level are more important than space HVAC systems. [German] Im Rahmen eines der weltweit groessten Forschungsprojekte zum Thema 'Sick Building Syndrome' wurden in Deutschland zwischen 1995 und 1999 umfangreiche Untersuchungen durchgefuehrt mit dem Ziel, die Ursachen und Folgen von Befindlichkeitsstoerungen in Buerogebaeuden zu ermitteln. Insgesamt wurden 8 klimatisierte und 6 nicht klimatisierte Gebaeude, 40 raumlufttechnische Anlagen und 1497 Arbeitsplaetze untersucht sowie ueber 4.500 Personen befragt. Die Ergebnisse erlauben zum ersten Mal einen direkten Vergleich der gemessenen physikalischen, biologischen und chemischen Werte mit den subjektiven Angaben (Fragebogendaten) an klimatisierten und nicht klimatisierten Arbeitsplaetzen. Die Auswertung zeigt, dass die Konzentration der Anlagen und deren hygienischer Wartungszustand einen Einfluss auf die Befindlichkeit der Mitarbeiter haben. Gebaeude mit gut geplanten und gewarteten RLT-Anlagen schneiden in der Bewertung sogar besser ab als nicht klimatisierte Gebaeude. Die groessten

  14. SRTM-DEM AND LANDSAT ETM+ DATA FOR MAPPING TROPICAL DRY FOREST COVER AND BIODIVERSITY ASSESSMENT IN NICARAGUA

    Directory of Open Access Journals (Sweden)

    Brett G. Dickson

    2008-08-01

    Full Text Available Tropical dry and deciduous forest comprises as much as 42% of the world’s tropical forests, but hasreceived far less attention than forest in wet tropical areas. Land use change threatens to greatly reducethe extent of dry forest that is known to contain high levels of plant and animal diversity. Forest fragmentationmay further endanger arboreal mammals that play principal role in the dispersal of large seeded fruits, plantcommunity assembly and diversity in these systems. Data on the spatial arrangement and extent of dryforest and other land cover types is greatly needed to enhance studies of forest fragmentation effects onanimal populations. To address this issue, we compared two Random Forest decision tree models forland cover classification in a Nicaraguan tropical dry forest landscape with and without the use of terrainvariables derived from Space Shuttle Radar and Topography Mission digital elevation data (SRTM-DEM.Landsat Enhanced Thematic Mapper (ETM+ bands and vegetation indices were the principle source ofspectral variables used. Overall classification accuracy for nine land cover types improved from 82.4% to87.4% once terrain and spectral predictor variables were combined. Error matrix comparisons showedthat class accuracy was significantly greater (z = 2.57, p-value < 0.05 with the inclusion of terrain variables(e.g., slope, elevation and topographic wetness index in decision tree models. Variable importance metricsindicated that a corrected Normalized Difference Vegetation Index (NDVIc and terrain variables improveddiscrimination of forest successional types and wetlands in the study area. Results from this study demonstratethe capability of terrain variables to enhance land cover classification and habitat mapping useful tobiodiversity assessment in tropical dry forest.

  15. Caregiver burden assessed in dementia care networks in Germany: findings from the DemNet-D study baseline.

    Science.gov (United States)

    Laporte Uribe, Franziska; Heinrich, Steffen; Wolf-Ostermann, Karin; Schmidt, Sylvia; Thyrian, Jochen René; Schäfer-Walkmann, Susanne; Holle, Bernhard

    2017-09-01

    This paper aimed to describe the burden experienced by informal caregivers supporting a person with dementia (PwD) who lives at home and utilizes a dementia care network (DCN), to investigate the factors that are associated with caregiver burden, and to identify possible differences in caregiver burden among different types of DCNs. This study was part of a multi-center, interdisciplinary evaluation of DCNs in Germany (DemNet-D). Cross-sectional data were collected in face-to-face interviews with people with dementia (PwDs) and their caregivers, and 13 DCNs were represented. Standardized questionnaires were used to assess caregiver burden, challenging PwD behaviors, functional competence and caregiver health status. Based on qualitative data, four DCN governance types were used in a multivariate analysis of burden categories. There were 560 PwD-caregiver dyads enrolled in the study. Informal caregivers (n = 536) reported a low-to-moderate burden associated with PwD characteristics (instrumental activities of daily living, challenging behaviors) and caregiver characteristics (gender) as well as the relationship between the caregivers and PwDs. Women felt more burdened but also showed higher levels of personal development. No differences were observed among the different DCN governance types. DCNs might contribute toward moderate to low caregiver burden. Indicators of positive caregiving aspects can be used by DCNs to advance support structures for informal caregivers drawing upon interventions already established for other community settings. Particular interest should be paid to female and spousal caregivers who might be in in need of greater and/or different kinds of support.

  16. Mythological ears, a real deformity: A case of bilateral Stahl's ears in ...

    African Journals Online (AJOL)

    familial tendency, with 75% expression in identical twins.[1] An abnormal course of the transverse auricular muscle was found by Yotsuyanagi et al., which was postulated to be of aetiological significance.[2]. Clinically the condition may be recognised by a third crus with a flattened antihelix and a malformed scapha, creating ...

  17. Nur dem Schnabel nach?

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Schulten, Klaus; Greiner, Walter

    2010-01-01

    Tiere haben offenbar die Fähigkeit, das Magnetfeld der Erde wahrzunehmen und sich daran zu orientieren. Seit Mitte der 1960er Jahre gelang es, diesen Magnetsinn bei höheren Organismen experimentell nachzuweisen. Am besten untersucht ist heute der ``Magnetkompass'' der Zugvögel. Dennoch gelten...

  18. Papilødem

    DEFF Research Database (Denmark)

    Kromann Nielsen, Marianne; Hamann, Steffen

    2015-01-01

    Optic disc oedema describes the nonspecific, localized swelling of the optic nerve head regardless of aetiology. Therefore, differentiating among the various aetiologies depends on a thorough history and knowledge of the clinical characteristics of the underlying conditions. Papilloedema strictly...... refers to optic disc oedema as a consequence of elevated intracranial pressure. It is usually a bilateral condition and visual function is preserved until late. Optic disc oedema caused by an anterior optic neuropathy is usually unilateral and accompanied by the loss of visual function....

  19. DEM Particle Fracture Model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boning [Univ. of Colorado, Boulder, CO (United States); Herbold, Eric B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Regueiro, Richard A. [Univ. of Colorado, Boulder, CO (United States)

    2015-12-01

    An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts. Also Weibull theory is introduced to consider the statistics and size effects on particle strength. Finally, high strain-rate split Hopkinson pressure bar experiment of silica sand is simulated using this newly developed model. Comparisons with experiments show that our particle fracture model can capture the mechanical behavior of this experiment very well, both in stress-strain response and particle size redistribution. The effects of density and packings o the samples are also studied in numerical examples.

  20. DEM - distribution energy management

    Energy Technology Data Exchange (ETDEWEB)

    Seppaelae, A.; Kekkonen, V.; Koreneff, G. [VTT Energy, Espoo (Finland)] [and others

    1998-08-01

    The electricity market was de-regulated in Finland at the end of 1995 and the customers can now freely choose their power suppliers. The national grid and local distribution network operators are now separated from the energy business. The network operators transmit the electric power to the customers on equal terms regardless from whom the power is purchased. The Finnish national grid is owned by one company Finnish Power Grid PLC (Fingrid). The major shareholders of Fingrid are the state of Finland, two major power companies and institutional investors. In addition there are about 100 local distribution utilities operating the local 110 kV, 20 kV and 0.4 kV networks. The distribution utilities are mostly owned by the municipalities and towns. In each network one energy supplier is always responsible for the hourly energy balance in the network (a `host`) and it also has the obligation to provide public energy prices accessible to any customer in the network`s area. The Finnish regulating authorities nominate such a supplier who has a dominant market share in the network`s area as the supplier responsible for the network`s energy balance. A regulating authority, called the Electricity Market Centre, ensures that the market is operating properly. The transmission prices and public energy prices are under the Electricity Market Centre`s control. For domestic and other small customers the cost of hourly metering (ca. 1000 US$) would be prohibitive and therefore the use of conventional energy metering and load models is under consideration by the authorities. Small customer trade with the load models (instead of the hourly energy recording) is scheduled to start in the first half of 1998. In this presentation, the problems of energy management from the standpoint of the energy trading and distributing companies in the new situation are first discussed. The topics covered are: the hourly load data management, the forecasting and estimation of hourly energy demands, optimization of energy production, short-term trade management, retail tariff design and planning of power purchase from the markets