1,721,042 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Möglichkeiten und Grenzen der Frühwarnung und Vorhersage von extremen hydrologischen Ereignissen
No full textVariations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Impact of changing land use on the water balance and the vitality of alluvial forests at a river oasis at the Tarim River (China)
No full textZur Abschätzung der Auswirkungen von Landnutzungs- und Klimaänderungen wurde der Wasserhaushalt einer Region bei Yengibazar (Xinjiang, China) untersucht. Die durchgeführten Berechnungen zeigen, dass die natürlichen Überschwemmungsgebiete den größten Einfluss auf die Grundwasserneubildung haben. Zudem konnte nachgewiesen werden, dass Interaktionen zwischen Bewässerungsgebieten und angrenzender natürlicher Vegetation bestehen. Die Ergebnisse machen deutlich, dass zeitnah ein integriertes Wasserressourcen-Management entwickelt werden muss.To estimate the impact of land use and climate change, the water balance of an area at Yengibazar (Xinjiang, China) was analysed. The calculations show that the natural floodplains have the highest influence on the groundwater recharge. Furthermore, an interaction between irrigated areas and the natural vegetation could be detected. As a consequence of this work, a water resources management should be developed soon
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Anwendung des Soil and Water Assessment Tool (SWAT) in alpinen Einzugsgebieten: Herausforderungen und Lösungen
No full textThis work aims to improve the application of SWAT in alpine catchments by rational use of available data considering model structure. The selection of optimal precipitation input, utilization of snow data during calibration, and consideration of energy price data to reproduce hydropeaking, have the common effect of improving the reliability of model results by considering more observed information. This could benefit the local water management practices and even hydrological hazard forecast.Das Ziel dieser Arbeit ist es, die Anwendbarkeit des SWAT in alpinen Einzugsgebieten durch die intelligente Nutzung von verfügbarer Daten unter Berücksichtigung der Modellstruktur, zu verbessern. Die Auswahl eines optimalen Niederschlagsdatensatzes, die Nutzung von Schneedaten während der Kalibrierung und die Berücksichtigung von Energiepreisinformationen zur Simulation des Hydropeakingeffekts tragen dazu bei, die Zuverlässigkeit der Modellresultate zu erhöhen. Dies kann die Planung wasserwirtschaftlicher Maßnahmen, sowie die Vorhersage hydrologisch-bedingter Naturgefahren verbessern
Ein GIS-basiertes Planungstool zur Unterstützung von Kommunen in ihrer Anpassung an Starkniederschläge
No full textHuman-caused climate change is intensifying the frequency and intensity of heavy rain events. Heavy rains are generally understood as precipitation events with a high amount of rainfall. These events usually occur locally. Due to their high intensity, they can lead to flash floods, floods, erosion and overloading of the sewer network. Although climate change adaptation and adaptation to heavy rain events have become integral items of the climate policy agenda over the last decade, they still pose major challenges for German municipalities. In this thesis, the key challenges hindering municipalities when planning and implementing measures to adapt to heavy rain events are investigated and a novel tool to mitigate these challenges is proposed. The status quo in municipalities and the challenges they face were established using a survey, detailed one-on-one interviews and extensive literature research. On the basis of the results obtained, the hypothesis is formulated that municipal adaptation planning can be improved by instruments that support interdisciplinary communication, capacity building and/or decision-making. A GIS-based planning tool is developed to help planners assess the need for action as well as to determine the adaptation potential of municipalities. The latter includes their capabilities to formulate conceptual plans, which can be used to support decision-making in the adaptation and planning process on the appropriate protective measures to implement. The hypothesis and usefulness of the planning tool were verified in a target group workshop. The overriding root cause of many of the challenges can be found in the lack of legislative requirements or institutional agreements. Specifically, there are challenges posed by existing or non-existing legal bases, coordination mechanisms within and between sectors, unclear roles and responsibilities and differences in planning cultures. These make it difficult to assess the need for action and reach consensus on the cost and effectiveness of individual measures. Uncertainties in climate change projections complicate finding agreement on adaptation strategies, putting existing risk management approaches to the test. Furthermore, climate change adaptation strategies necessarily involve a wide range of stakeholders with different interests and understanding of the issues. These uncertainties affect municipal planning practice. At the municipal level, the main obstacles can be localised in the initial planning phase, the identification of the need for action and the adaptation potential as well as developing options and their assessment. The rather restrained strategy development and implementation to date is attributed, among other things, to scarce financial and human resources, institutional obstacles. Moreover, not only an assessment of cost and effectiveness of protective measures is needed but also instruments and tools to support decision-making processes. Through capacity development, targeted approaches to communication and awareness raising, the creation of a common adaptation culture is achieved. It is important that the different disciplines involved (e.g. water managers & municipal planning) learn from each other in order to build and expand each other's awareness and capacities with regard to climate change adaptation. Tools, methods, technologies and practices can be used to support collaboration and explicit intra-municipal communication. Thereby, synergies are exploited and obstacles and restrictions are recognized early on and can be jointly eliminated. The GIS planning tool developed in this thesis encourages communication and collaboration between planning experts. It is suitable for determining the municipal’s adaptation potentials as well as the need for action during heavy rain events. As such, it contributes to finding a common consensus in issues related to adaptation to heavy rain events
Homogenization and analysis of hydrological time series
No full textIn hydrological studies, it is very important to properly analyze the relationship among the different components of the water cycle, due to the complex feedback mechanisms typical of this system. The analysis of available time series is hence a fundamental step, which has to be performed before any modeling activity. Moreover, time series analysis can shed light over the spatial and temporal dynamics of correlated hydrological and climatological processes. In this work, we focus on three tools applied for time series analysis: homogeneity tests, wavelet analysis and copula analysis. Homogeneity tests allow to identify a first important kind of variability in the time series, which is not due to climate nor seasonal variability. Testing for inhomogeneities is therefore an important step that should be always performed on a time series before using it for any application. The homogenization of snow depth data, in particular, is a challenging task. Up to now, it has been performed analyzing available metadata, which often present contradictions and are rarely complete. In this work, we present a procedure to test the homogeneity of snow depth time series based on the Standard Normal Homogeneity Test (SNHT). The performance of the SNHT for the detection of inhomogeneities in snow depth data is further investigated with a comparison experiment, in which a dataset of snow depth time series relative to Austrian stations has been analyzed with both the SNHT and the HOMOP algorithm. The intercomparison study indicates that the two algorithms show comparable performance.
The wavelet transform analysis allows to obtain a different kind of information about the variability of a time series. In fact, it determines the different frequency content of a signal in different time intervals. Moreover, the wavelet coherence analysis allows to identify periods where two time series are correlated and their phase shift. We apply the wavelet transform to a dataset of snow depth time series of stations distributed in the Adige catchment and on a dataset of 16 discharge time series located in the Adige and in the Inn catchments. The same datasets are used to perform a wavelet coherence analysis considering the Mediterranean Oscillation Index (MOI) and the North Atlantic Oscillation Index (NAOI). This analysis highlights a difference in the behavior of the snow time series collected below and above 1650 m a.s.l.. We also observe a difference between low and high elevation sites in the amount of mean seasonal snow depth and snow cover duration. More interestingly, snow time series collected at different elevations respond differently to temperature and more in general to climate changes. The wavelet analysis allows us also to distinguish between gauging stations belonging to different catchments, while the wavelet coherence analysis revealed non-stationary correlations with the MOI and NAOI, indicating a very complex relation between the measured quantities and climatic indexes. Finally the application of copulas allows modeling the marginal of each variable and their dependence structure independently. We apply this technique to two relevant cases. First we study snow related variables in relation with temperature, the NAOI and the MOI, which we already investigated with the wavelet coherence analysis. Then we model flood events registered at two stations of the Inn river: Wasserburg and Passau. This last analysis is performed with the goal of predicting future flood events and derive construction parameters for retention basins. We test three different combinations of variables (direct peak discharge-direct volume, direct peak discharge-direct volume-rising time-base flow, direct peak discharge-direct volume-rising time-moving threshold) describing the flood events and compare the results. The consistency in the results indicates that the proposed methodology is robust and reliable. This study shows the importance of approaching the analysis to hydrological time series from several points of view: quality of the data, variability of the time series and relation between different variables. Moreover, it shows that integrating the use of various time series analysis methods can greatly improve our understanding of the system behavior
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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