1,720,984 research outputs found
An efficient calibration-constrained Monte Carlo technique for evaluating model predictive error
No full textWe describe a new Monte Carlo (MC) technique that reduces the computational burden of calibration-constrained MC using the concept of the calibration null space. In the new MC approach, the model is calibrated using a subspace regularization method such as Truncated Singular Value Decomposition (TSVD) or the hybrid Tikhonov-TSVD approach described by Tonkin & Doherty (2005). Next, a stochastic parameter field generator is used to produce many realizations of the parameter field. For each realization, a difference is formed between the stochastic field and the calibration field. This difference is projected onto the calibration null space determined through the calibration process, and added to the calibration field. If the model is no longer calibrated, the underlying field is re-estimated with the null-space-difference field "riding on its back". If this can be undertaken using pre-calculated sensitivities, conditioning may require only a very small number of model runs. The new MC approach can rapidly produce a large number of conditioned stochastic fields, for use in assessing the potential error in a wide range of predictions. Copyrigh
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Validation and Intercomparison of Different Updating Procedures for Real-Time Forecasting
No full textThe paper presents a classification and a review of the updating procedures currently used in real-time flood forecasting modelling. On the basis of results from the WMO project ‘Simulated Real-Time Intercomparion of Hydrological Models’, comprising more than 10 commonly used hydrological models and a variety of different updating procedures, an analysis of the relative importance of updating procedures and hydrological simulation models is provided. In particular, an intercomparison is made beteween two models (NAMS11/MIKE11 and NAMKAL) consisting of the same hydrological model (NAM conceptual rainfall-runoff) but containing different routing modules (linear reservoirs versus hydraulic routing) and different updating procedures (error prediction versus state variable updating based on an extended Kalman filter). A main conclusion is that updating procedures significantly improve the performances of hydrological models for short-range forecasting. Furthermore, there are no clear conclusions regarding which type of updating procedure performs the better. However. intercomparison of the NAMS11 and NAMKAL models indicates that the extended Kalman filter is marginally better than an error prediction model in cases where the basic hydrological model simulation is good. Finally, it is concluded that the basic simulation is very essential for accurate forecasts, and that the better the basic simulations are the better the updating routines in general function. This puts emphasis on the importance of thoroughly calibrating and validating the hydrological simulation models before applying them together with updating routines in operational real-time forecasting.</jats:p
Pigs, prawns and power houses: Politics in water resources management
No full textNormative ideals for 'good water management' have proliferated the last twenty years. However, evidence of effective implementation is scarce. This paper analyzes cases from India, the Mekong and Denmark where attempts have been made to translate water management ideals into practice. The purpose is to demonstrate the importance of politics and power for water management processes and their outcomes. The concept of social learning is applied in order to understand the dynamic interplay between actors, institutions and power in the political processes involved. It is argued that the political economy of water tends to vest the stronger stakeholders with an interest in upholding the status quo. Consequently, social learning typically centers on the 'low lying fruits' that does not challenge the prevailing distribution of resources. The authors, Kurt Mørck Jensen, Rane Baadsgaard Lange, and Jens Christian Refsgaard argue that strategic approaches looking outside the 'water box' are necessary to foster deeper changes in water resources management in both developing and developed countries
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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