Integrated nutrient transport modelling with respect to the implementation of the European WFD: The Weiße Elster Case Study, Germany

The goal of the European Water Framework Directive (WFD) is to protect and enhance the status of aquatic and terrestrial ecosystems. To reach this objective an integrated methodology for the implementation of the WFD is essential. The methodology presented was developed within an interdisciplinary research project on the highly polluted 4th order Weiße Elster River basin, a large subcatchment of the Saale basin (Germany), which is part of the UNESCO-IHP HELP program. The project focuses on nutrient management in order to achieve a good ecological status of surface waters. The paper focuses on an integrated modelling of nitrogen transport and comprises combined terrestrial and in-stream transport processes. The mitigation of diffuse and point sources pollution is thereby essential to meet the environmental objectives. Land-use scenarios on both organic farming systems and best management practices were analysed and compared with different strategies to reduce point source. The results show that the possible reduction of nitrogen inputs from point sources is much lower compared to the reduction of diffuse inputs from agricultural land use. The results on in-stream nitrogen transformation show that different morphological factors influence the nitrogen retention considerably. The potential of management measures to reduce nitrogen loads by river restoration measures seems to be limited. This is caused by infrastructural facilities that restrict attaining a natural state of river morphology.Keywords: river basin management, nutrient transport, river restoration, SWAT, WAS

Unconventional magnetism in all-carbon nanofoam

We report production of nanostructured carbon foam by a high-repetition-rate, high-power laser ablation of glassy carbon in Ar atmosphere. A combination of characterization techniques revealed that the system contains both sp2 and sp3 bonded carbon atoms. The material is a novel form of carbon in which graphite-like sheets fill space at very low density due to strong hyperbolic curvature, as proposed for ?schwarzite?. The foam exhibits ferromagnetic-like behaviour up to 90 K, with a narrow hysteresis curve and a high saturation magnetization. Such magnetic properties are very unusual for a carbon allotrope. Detailed analysis excludes impurities as the origin of the magnetic signal. We postulate that localized unpaired spins occur because of topological and bonding defects associated with the sheet curvature, and that these spins are stabilized due to the steric protection offered by the convoluted sheets.Comment: 14 pages, including 2 tables and 7 figs. Submitted to Phys Rev B 10 September 200

Governing urban accessibility: moving beyond transport and mobility

Access to people, goods, ideas and services is the basis of economic development in cities. The better this access, the greater the economic benefits through economies of scale, agglomeration effects and networking advantages. The way in which cities facilitate accessibility also impacts directly on other key aspects of human development, social inclusion and well-being. Accessibility is created through a complex interplay of urban form and transport systems. Thus, governing urban accessibility requires moving beyond conventional urban transport considerations linked to mobility and movement. Such a re-framing implies a far greater recognition of urban form characteristics like land use, distribution of densities and urban design, in addition to transport characteristics like infrastructures, service levels and travel speeds. A new interface between these characteristics has emerged as a result of shared mobility systems, putting additional pressure on city governments to act as system integrators. Based on a literature review, empirical insights from a global survey and the case-study cities of London, NYC and Berlin, this paper explores the institutional capacities of shifting from governing urban transport to urban accessibility. The evidence shows that there are entrenched misalignments which may impact negatively on the capacity to pair planning and policies essential for delivering better accessibility. Furthermore, it is clear that “hierarchies” and “networks” are not mutually exclusive when it comes to integrated governance of accessibility. The findings also suggest that cities may be better equipped to integrate shared mobility and consider mobility as a service than to pursue more wide-ranging metropolitan accessibility policies

Radar Clutter Backscattering Simulation for Specific Sites

The state of development of the surface clutter prediction model DORTE is presented. This simulation program utilizes Digital Elevation Models and land use information to calculate reflectivity maps for specific sites with optional statistical variation using semi-empirical and statistical clutter models. Land use information is provided by the database CORINE of the European Environment Agency. A simulated map is compared to a SAR image

Detection Probability of a Ground-based Radar

Radar cross section histograms will be presented for various depression angles and terrain types using various semi-empirical clutter models generated by Monte-Carlo simulation. The calculation includes terrain parameters such as roughness, ground humidity and thickness of vegetation cover

Radardetektionswahrscheinlichkeiten aus Rückstreuquerschnitts-Verteilungen

Zur Berechnung von Radardetektionswahrscheinlichkeiten entlang einer Trajektorie aus zweidimensionalen RCS -Diagrammen müssen zwei Programme nacheinander verwendet werden: „Fluktuation“ und „Swerling“. Im Folgenden werden diese beiden Programme und ihre theoretischen Grundlagen näher beschrieben

Landclutter - Rechnersimulation von monostatischem Radarrückstreuhintergrund

Nach einer Einführung in die Problematik werden verschiedene Modelle zur Clutterberechnung vorgestellt. Die statistische Variation von Clutter wird besprochen. Simulationsergebnisse eines Programms zur Berechnung des monostatischen Radarstörhintergrunds für ein beliebiges vorgegebenes Gelände werden gezeigt unter Verwendung der Landnutzungsdatenbank CORINE

Landclutter

Nach einer Einführung in die Problematik werden verschiedene Modelle zur Clutterberechnung vorgestellt. Die statistische Variation von Clutter wird besprochen. Simulationsergebnisse eines Programms zur Berechnung des monostatischen Radarstörhintergrunds für ein beliebiges vorgegebenes Gelände werden gezeigt

Site Specific Radar Clutter Backscattering Simulation

Knowledge of radar clutter is essential to determine the radar range or the detectability of manmade objects embedded in a natural environment. In this article the computer model DORTE is presented. This simulation program estimates radar clutter backscattering for specific sites represented by digital elevation models. In the current version of the program the output is a reflectivity map. Shadowed areas, which are not accessible to radar at frequencies above 1 GHz, are identified by means of a specialized hidden surface algorithm. Semi-empirical and statistical clutter models are assigned to each terrain cell utilizing the CORINE land use information database of the European Environment Agency. The predicted average clutter value can optionally be statistically varied. An exemplary simulation is compared to a reflectivity map derived from a SAR image and shows satisfactory correlatio

Phononeninduzierte Röntgenquantenschwebungen

In der vorliegenden Arbeit wurden mehrere Röntgeninterferometer hergestellt. Dabei wurde die Funkenerosion als ein in diesem Bereich neues Herstellungsverfahren angewendet. Die erzielten Kontrastverhältnisse betrugen bis zu 73 Prozent und sind damit vergleichbar mit guten Geräten anderer Gruppen, die auf herkömmliche Art hergestellt wurden. Mit diesen Interferometern wurden sowohl statische Messungen zu deren Charakterisierung vorgenommen, als auch die Eigenschaften verschiedener Phasenschieber bestimmt. Der Einfluß von Wärme und Licht auf den Analysatorsteg eines Interferometers wurde untersucht. Dabei zeigten sich in beiden Fällen eine Verringerung des Kontrastverhältnisses und eine Veränderung der Phasenlage des leeren Interferometers. Zur Untersuchung der Wechselwirkung von Ultraschall mit Röntgenphotonen wurden an den Außenseiten der Spiegelstege der Interferometer X-Schnitt-Quarze mit einer Resonanzfrequenz von ungefähr 10 MHz angebracht. Die Beeinflussung der einzelnen Röntgenteilstrahlen konnte durch zeitaufgelöste Messung der Zählraten relativ zur Anregungsphase des Quarzes nachgewiesen werden. Röntgenquantenschwebungen konnten mit verschiedenen Meßkonfigurationen in verschiedenen Frequenzbereichen von 76 kHz bis hinunter zu 100 mHz nachgewiesen werden. Das tatsächliche Vorliegen einer Schwebungserscheinung wurde durch die Verwendung einer radioaktiven 57Co-Quelle anstelle des Röntgengenerators überprüft. Es zeigte sich, daß mit unserer Apparatur ohne weitergehende Modifikationen Energiedifferenzen bis hinunter zu 124 zeV detektierbar sind. Durch Verlegen des Meßaufbaus in einen temperaturstabilisierten Bereich läßt sich diese Grenze noch weiter nach unten verschieben. Die erzielbare Energieempfindlichkeit hängt von der Meßdauer ab und betrug in unserem Fall maximal 15,5 zeV. Das entspricht einer relativen Energieauflösung von 1,93x10(-24)