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A satellite-based climatology of wind-induced surface temperature anomalies for the Antarctic
Get PDFIt is well-known that katabatic winds can be detected as warm signatures in the surface temperature over the slopes of the Antarctic ice sheets. For appropriate synoptic forcing and/or topographic channeling, katabatic surges occur, which result in warm signatures also over adjacent ice shelves. Moderate Resolution Imaging Spectroradiometer (MODIS) ice surface temperature (IST) data are used to detect warm signatures over the Antarctic for the winter periods 2002–2017. In addition, high-resolution (5 km) regional climate model data is used for the years of 2002 to 2016. We present a case study and a climatology of wind-induced IST anomalies for the Ross Ice Shelf and the eastern Weddell Sea. The IST anomaly distributions show maxima around 10–15K for the slopes, but values of more than 25K are also found. Katabatic surges represent a strong climatological signal with a mean warm anomaly of more than 5K on more than 120 days per winter for the Byrd Glacier and the Nimrod Glacier on the Ross Ice Shelf. The mean anomaly for the Brunt Ice Shelf is weaker, and exceeds 5K on about 70 days per winter. Model simulations of the IST are compared to the MODIS IST, and show a very good agreement. The model data show that the near-surface stability is a better measure for the response to the wind than the IST itself
Unterricht partizipativ gestalten
Get PDFFachunterricht ist der zentrale Erfahrungsraum im Sozialisationsumfeld Schule. Er prägt schon allein aufgrund seines hohen zeitlichen Anteils im Tagesverlauf und der grundlegenden Funktion von Schule Handeln und Wahrnehmung von Lehrpersonen und Lernenden. Umso wichtiger ist es, ihn in die Gestaltung einer demokratischen Schulkultur einzubeziehen
Feedbackkultur im Unterricht: Miteinander besser werden
Get PDFFeedback in der Schule? Das bedeutet häufig eine kurze Rückmeldung der Lehrer*innen an die Schüler*innen zu deren Mitarbeit. Dabei bietet eine etablierte Feedbackkultur im Unterricht breite Möglichkeiten, demokratisches Handeln zu üben und die Unterrichtsqualität zu verbessern, und muss keineswegs nur einseitig ausfallen
Finding behavioral parameterization for a 1-D water balance model by multi-criteria evaluation
Get PDFEvapotranspiration is often estimated by numerical simulation. However, to produce accurate simulations, these models usually require on-site measurements for parameterization or calibration. We have to make sure that the model realistically reproduces both, the temporal patterns of soil moisture and evapotranspiration. In this study, we combine three sources of information: (i) measurements of sap velocities; (ii) soil moisture; and (iii) expert knowledge on local runoff generation and water balance to define constraints for a “behavioral” forest stand water balance model. Aiming for a behavioral model, we adjusted soil moisture at saturation, bulk resistance parameters and the parameters of the water retention curve (WRC). We found that the shape of the WRC influences substantially the behavior of the simulation model. Here, only one model realization could be referred to as “behavioral”. All other realizations failed for a least one of our evaluation criteria: Not only transpiration and soil moisture are simulated consistently with our observations, but also total water balance and runoff generation processes. The introduction of a multi-criteria evaluation scheme for the detection of unrealistic outputs made it possible to identify a well performing parameter set. Our findings indicate that measurement of different fluxes and state variables instead of just one and expert knowledge concerning runoff generation facilitate the parameterization of a hydrological model
Possibilités juridiques de la participation des élèves en classe : Un regard sur la Grande Région
Get PDFVorrede zur Festschrift für Gerhart Darmstadt
Get PDFVorrede aus der Festschrift "Barock.Violoncello." aus Anlaß des 60. Geburtstages des Barockcellisten Gerhart Darmstad
Coastal Urbanization and Urban Land-use Change
Get PDFThe impacts of intense urbanization and associated urban land-use change along coastlines is vast and unprecedented. Several coasts of the world have been be subjected to human-induced coastal changes and it is imperative to monitor, assess and quantify them. This paper provides the state-of-the-art discourses on the changing dynamics of urban land-use driven by the forces of urbanization. Drawing on extant literature mainly from Web of Science and Google scholar, the status quo of the spatio-temporal dynamics of urbanization and urban change processes were explored with specific focus on global, Africa, Ghana and an actual case of Accra coast. Findings show whilst urbanization continues to increase exponentially, urban land also continue to change markedly. Current trends and patterns shows that changing urban dynamics exhibit are distinctly different from that of the past. Particularly, the rate, magnitude, geographic location, urban forms and functions are changing. In the specific case of Accra coast, there is general trend of urbanization moving outwards, i.e. from the core city centre towards the peripheral areas. Additionally, spatial urban pattern is dominated by urban sprawl, characterized by the cyclical process of diffusion and coalescence. The processes of urbanization are further exacerbated within coastal areas with a new and unique spatial urban form, “tourism urbanization” emerging. This new urban form is largely driven by rapid expansion of tourist infrastructure, developing at the instance of government policy to develop coastal tourism. In addition, the coastal conurbation of Accra-Tema is a powerful hub for industrial and commercial activities, which is drawing huge “humanline” to- wards the coastline. The literature illustrates that contemporary approaches and conceptualizations for urbanization and urban land-use change analysis be extended particularly from the mere focus on statistical classifications of cities in different size categories. With the urban fringe spreading outwardly, it should be kept in mind that new forms of urban settlements are emerging along with varying sizes. Considering the multiple scales, magnitude and rates involved as well as the geospatial patterns of urban change processes, experimental case studies that include coastal cities, Peri-urban fringes and interconnections with rural areas across a range of urbanization processes is essential and very urgent
Copositivity in Infinite Dimension
Get PDFMany combinatorial optimization problems on finite graphs can be formulated as conic convex programs, e.g. the stable set problem, the maximum clique problem or the maximum cut problem. Especially NP-hard problems can be written as copositive programs. In this case the complexity is moved entirely into the copositivity constraint.
Copositive programming is a quite new topic in optimization. It deals with optimization over the so-called copositive cone, a superset of the positive semidefinite cone, where the quadratic form x^T Ax has to be nonnegative for only the nonnegative vectors x. Its dual cone is the cone of completely positive matrices, which includes all matrices that can be decomposed as a sum of nonnegative symmetric vector-vector-products.
The related optimization problems are linear programs with matrix variables and cone constraints.
However, some optimization problems can be formulated as combinatorial problems on infinite graphs. For example, the kissing number problem can be formulated as a stable set problem on a circle.
In this thesis we will discuss how the theory of copositive optimization can be lifted up to infinite dimension. For some special cases we will give applications in combinatorial optimization.Viele kombinatorische Optimierungsprobleme können als konvexe Probleme über einem Kegel formuliert werden, beispielsweise das stabile Mengen Problem, das Cliquenproblem oder das Problem des maximalen Schnitts. Insbesondere NP-schwere Probleme können als copositive Optimierungsprobleme formuliert werden. Hierbei liegt die Schwierigkeit des neuen Problems vollständig in der Copositivitätsbedingung.
Copositive Optimierung ist ein vergleichsweise neues Thema in der Optimierung. Es behandelt die Optimierung über dem sogenannten copositiven Kegel, welcher eine Obermenge des positiv semidefiniten Kegels darstellt. Sein Dualkegel ist der Kegel der vollständig positiven Matrizen, in welchem alle Matrizen enthalten sind, die als Summe von nichtnegativen, symmetrischen Vektor-Vektor-Produkten zerlegt werden können. Die zugehörigen Optimierungsprobleme haben eine lineare Zielfunktion, lineare Nebenbedingungen in der Matrixvariable und eine Kegelbedingung.
Manche Optimierungsprobleme können als kombinatorische Probleme über unendlich dimensionalen Graphen formuliert werden, wie zum Beispiel die Berechnung der sogennanten Kusszahl, welche als stabile Mengen Problem über der Sphäre beschrieben werden kann. In der vorliegenden Arbeit werden wir diskutieren, inwieweit das Konzept der Copositivität in einem unendlichdimensionalen Raum verallgemeinert werden kann. Für Spezialfälle werden wir Anwendungen in der kombinatorischen Optimierung präsentieren
Le conseil de coopération du point de vue des élèves
Get PDFLa mise en œuvre d’un conseil de coopération est liée à l’espoir de renforcer les compétences démocratiques des élèves. Une étude empirique1 réalisée au Lycée Nic Biever de Dudelange a analysé les compétences réellement acquises par les participant(e)s grâce à cette méthode d’éducation à la démocratie ainsi que l’impact du conseil de coopération sur la classe
mateneen - Praxishefte Demokratische Schulkultur 03/2019: Partizipation im Unterricht
Get PDFDie Praxishefte Demokratische Schulkultur erscheinen halbjährlich und bieten Schulleitungen und Schulpersonal theoretische Grundlagen und praxisorientierte Anleitungen zur demokratiepädagogischen Schulentwicklung. Jedes Themenheft ist jeweils einer demokratiepädagogischen Bauform oder strategischen Frage der Schulentwicklung gewidmet. Die Praxishefte werden allen Luxemburger Schulen als Printausgabe zur Verfügung gestellt und online mit zusätzlichen Materialien und in französischer Fassung vorgehalten