410 research outputs found

    Intrinsic subspace convergence in TDD MIMO communication

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    In numerical linear algebra, students encounter early the iterative power method, which finds eigenvectors of a matrix from an arbitrary starting point through repeated normalization and multiplications by the matrix itself. In practice, more sophisticated methods are used nowadays, threatening to make the power method a historical and pedagogic footnote. However, in the context of communication over a time-division duplex (TDD) multipleinput multiple-output (MIMO) channel, the power method takes a special position. It can be viewed as an intrinsic part of the uplink and downlink communication switching, enabling estimation of the eigenmodes of the channel without extra overhead. Generalizing the method to vector subspaces, communication in the subspaces with the best receive and transmit signal-to-noise ratio (SNR) is made possible. In exploring this intrinsic subspace convergence (ISC), we show that several published and new schemes can be cast into a common framework where all members benefit from the ISC.Peer Reviewe

    Multiple-Description l1-Compression

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    Historische Pfarr- und Konvents-Bibliothek St. Nikolaus Wipperfürth: Einführung und Inventar

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    Beiträge zur neueren Ordens- und Frömmigkeitsgeschichte / hrsg. von Eric W. Steinhauer Nr. 5 (2007) ISSN 1860-340

    De rettslige rammene for avtaler mellom påtalemyndigheten og siktede. En vurdering av plea bargaining-instituttet sin plass i den norske strafferettspleien

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    Tema for masteravhandlingen er å kartlegge hvilke muligheter påtalemyndigheten har til å inngå strafferettslige forlik med siktede. Avhandlingen er for det første et deskriptivt arbeid som skal besvare i hvilken grad den norske strafferettspleien åpner for strafferettslige forlik – en rettsdogmatisk analyse. Ettersom strafferettslige forlik ikke er en etablert del av den norske strafferettspleien, vil også normative vurderinger inngå under de fleste problemstillingene. Følgelig vil de lege ferenda vurderinger fortløpende søke å besvare om den norske strafferettspleien vil være tjent med konkrete plea bargaining-mekanismer. Videre rettes et kritisk blikk på straffeprosessutvalgets forslag om straffetilsagn

    An efficient first-order method for l1 compression of images

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    Motsättningen mellan styrning och innovationsförmåga - en multipel fallstudie

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    Syftet med uppsatsen är att påvisa hur innovativa företag arbetar med motsättningen mellan behovet av styrning kontra behovet av innovationsförmåga. Utifrån empirin har vi funnit belägg som stödjer vårt antagande om att det finns en motsättning mellan behovet av styrning kontra behovet av innovationsförmåga. Företagen handskas generellt med motsättningen genom att i stor utsträckning använda sig av styrformer som anses vara mer lösa i kombination med nyckelpersoner som driver innovationsprocessen

    Physical analysis of an Antarctic ice core-towards an integration of micro- and macrodynamics of polar ice

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    Microstructures from deep ice cores reflect the dynamic conditions of the drill location as well as the thermodynamic history of the drill site and catchment area in great detail. Ice core parameters (crystal lattice-preferred orientation (LPO), grain size, grain shape), mesostructures (visual stratigraphy) as well as borehole deformation were measured in a deep ice core drilled at Kohnen Station, Dronning Maud Land (DML), Antarctica. These observations are used to characterize the local dynamic setting and its rheological as well as microstructural effects at the EDML ice core drilling site (European Project for Ice Coring in Antarctica in DML). The results suggest a division of the core into five distinct sections, interpreted as the effects of changing deformation boundary conditions from triaxial deformation with horizontal extension to bedrock-parallel shear. Region 1 (uppermost approx. 450 m depth) with still small macroscopic strain is dominated by compression of bubbles and strong strain and recrystallization localization. Region 2 (approx. 450–1700 m depth) shows a girdle-type LPO with the girdle plane being perpendicular to grain elongations, which indicates triaxial deformation with dominating horizontal extension. In this region (approx. 1000 m depth), the first subtle traces of shear deformation are observed in the shape-preferred orientation (SPO) by inclination of the grain elongation. Region 3 (approx. 1700–2030 m depth) represents a transitional regime between triaxial deformation and dominance of shear, which becomes apparent in the progression of the girdle to a single maximum LPO and increasing obliqueness of grain elongations. The fully developed single maximum LPO in region 4 (approx. 2030–2385 m depth) is an indicator of shear dominance. Region 5 (below approx. 2385 m depth) is marked by signs of strong shear, such as strong SPO values of grain elongation and strong kink folding of visual layers. The details of structural observations are compared with results from a numerical ice sheet model (PISM, isotropic) for comparison of strain rate trends predicted from the large-scale geometry of the ice sheet and borehole logging data. This comparison confirms the segmentation into these depth regions and in turn provides a wider view of the ice sheet

    Delineating disorder-general and disorder-specific dimensions of psychopathology from functional brain networks in a developmental clinical sample

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    The interplay between functional brain network maturation and psychopathology during development remains elusive. To establish the structure of psychopathology and its neurobiological mechanisms, mapping of both shared and unique functional connectivity patterns across developmental clinical populations is needed. We investigated shared associations between resting-state functional connectivity and psychopathology in children and adolescents aged 5–21 (n =1689). Specifically, we used partial least squares (PLS) to identify latent variables (LV) between connectivity and both symptom scores and diagnostic information. We also investigated associations between connectivity and each diagnosis specifically, controlling for other diagnosis categories. PLS identified five significant LVs between connectivity and symptoms, mapping onto the psychopathology hierarchy. The first LV resembled a general psychopathology factor, followed by dimensions of internalising- externalising, neurodevelopment, somatic complaints, and thought problems. Another PLS with diagnostic data revealed one significant LV, resembling a cross-diagnostic case-control pattern. The diagnosis-specific PLS identified a unique connectivity pattern for autism spectrum disorder (ASD). All LVs were associated with distinct patterns of functional connectivity. These dimensions largely replicated in an independent sample (n = 420) from the same dataset, as well as to an independent cohort (n =3504). This suggests that covariance in developmental functional brain networks supports transdiagnostic dimensions of psychopathology.publishedVersio

    3D-Structure ofNEGIS shearmarginsfromradarstratigraphy

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    The North East Greenland Ice Stream (NEGIS) is delineated by well-defined shear margins, which are evident in the gradient of surface velocity field as well as in the surface topography, where they form troughs up to ten meters deep. In the upper part of the ice stream the margins appear not to be linked to bedrock topography. To understand this efficient system of mass transport towards the ocean it is essential to investigate the nature of the shear margins, as here very localized deformation decouples the inner ice stream from the slower flowing surrounding ice sheet. This process is influenced by several factors and feedback mechanisms, including the crystal fabric orientation, strain heating and localization of meltwater. In summary, the shear margins are area-wise a small part of the ice stream itself, but the processes leading to the localization of deformation are of similar importance for ice discharge as the processes enabling fast flow of the main trunk over the bed. We present results from an airborne radar survey with the AWI Ultra-Wide Band Radar system, covering an area 150 km upstream and 100 km downstream of the deep drilling site on the ice stream (EGRIP). Over the survey area the ice stream accelerates from 12 m/a to 75 m/a. We focus on the signatures of the shear margins in the radar data. In the regions of localized shear, the internal reflections in the radargrams show disturbances in the form of steep undulations, or chevron folds, which are intensified with ongoing shear. As the ice stream has been covered with 36 flow-perpendicular radar sections we are able to show the evolution of these characteristic signatures over the survey area, and thus, as an analog, over time. 3D-representations of the folded stratigraphic layers reveal how new folds are formed when the ice stream widens and how older structures are preserved in the outer part of the main trunk, where they are no longer subject to shear. Furthermore, we link the change of the shape of the internal reflections in the shear zones to a strain rate field calculated from high resolution flow velocities derived by TerraSAR-X data
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