1,721,146 research outputs found
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
Discussion of :identification of contaminant source location and release history in aquifers" by Mustafa M. Aral, Jiabao Guan, and Morris L. Maslia
No full text[Extract] The authors have presented an interesting approach for the characterization of unknown contaminant sources in groundwater systems. The solution results obtained for the illustrative source identification problem are no doubt encouraging. The most important aspect of this work is that the authors are able to locate the sources in a continuous scale by defining a potential location region and not discrete locations. This is a noteworthy contribution. This discusser would like to point out a few related issues that the authors could have raised or discussed to better enlighten the readers
STOCHASTIC OPTIMIZATION MODELS FOR LONG TERM PLANNING AND REAL TIME OPERATION OF RESERVOIR SYSTEMS
No full textFor efficient planning and real time operation of a reservoir system, it is desirable to formulate optimization models to serve as tools for decision making. In order to be a realistic representation of the decision making process, these models should also be able to incorporate the stochastic nature of streamflows as system inputs. The time steps considered in such models are of prime importance because the related aggregation or disaggregation of the inputs has significant effects on the uncertainties involved in the decision making process and directly influences the specification of optimal criteria in such models. This study is limited to two optimization models, one for longterm planning and seasonal operation and the other for real time daily operation of a reservoir system. Both of these models use chance constraints, assume Linear Decision Rules (LDR), and incorporate reliability criteria for different performance requirements. Both of these models are also capable of using multiple Linear Decision Rules, either based on different intervals of streamflow events or for different ranges of short term streamflow forecasts. To determine the effectiveness of a multiple LDR model as an aid to longterm planning and operation, its performance is evaluated for various \u27dimensions\u27 of the model and different input conditions. This model accounts for the Markovian dependence structure of streamflows by incorporating their distribution functions, conditioned on the streamflows in other seasons. The solutions obtained are tested in simulation of actual operation. The results are also compared with those for the original single LDR model. For real time daily operations, a model using similar concepts is proposed and evaluated. This model overcomes the myopic nature of short term operation, and uses distributions of actual streamflows conditioned on the forecasted values, thus accounting for uncertain forecasts. This model is also solved for different input conditions and the solutions are tested in a simulation of actual operation. The results of the evaluations and motivations for the results are discussed. Some of the basic characteristics of the decision making process for planning and management of reservoir systems are also explored
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
Optimization applications in water resources systems engineering
No full textOptimization tools and principles have made it possible to develop prescriptive models for optimal management of large scale water resources systems, incorporating ubiquitous uncertainties in the prediction of natural processes and the economic impacts. One of the areas of Civil Engineering which pioneered the use of optimization techniques is water resources systems planning, design, operation and management. Optimization tools are utilized to facilitate optimal decision making in the planning, design and operation of especially large scale water resources systems. The use of optimization tools as the most important component of Decision Support Systems are not confined only to the quantity aspect of water. The mitigation of polluted aquifers in a regional scale, operation of treatment plants and scheduling of effluent discharge in an optimal manner so as to control downstream pollution of rivers and other water bodies, designing of optimal strategies for reservoir releases for water quality augmentation, or maximizing hydropower generation, irrigation water supply etc. are only a few examples of using optimization tools for evolving economically efficient management strategies. Few earlier thoughts (in 2004-2005) on future prospects of optimal planning and management of water resources systems are recorded as an insight into the future. Some of these early observations are very relevant to current developments
Using evolutionary algorithms for continuous simulation of long-term reservoir inflows
No full textData-driven models provide upgradeable environments to simulate inflow to reservoirs. An important aspect in the development of an adaptive neural fuzzy inference system (ANFIS) model is to choose the correct procedure (i.e. efficient and effective) to train the model. In this study, a daily timescale ANFIS-based model was developed to simulate aggregated monthly long-term inflow to the Ross River reservoir in northern Queensland, Australia. The suitability of different evolutionary algorithms (EAs) was evaluated to train an ANFIS-based model, including a genetic algorithm (GA), particle swarm optimisation (PSO), shuffled frog leaping algorithm, biogeography-based optimisation, harmony search algorithm, differential evolution algorithm, invasive weed optimisation (IWO) and a cultural algorithm. Four indices - the root mean square error, Nash-Sutcliffe efficiency, reliability index and vulnerability index - were used to measure the performance of the model. It was found that application of either IWO, GA or PSO provided accurate simulated inflow time series. The outputs obtained using the other EAs were not sufficiently accurate. Use of a coupled EA-ANFIS-based model was found to improve the accuracy of simulating long-term monthly inflow compared with other models used in a few previous recent studies
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