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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
Study on the effect of chemical composition, processing temperature, and solidification velocity on the structure and solubility of fused magnesium thermophosphate.
No full textO presente trabalho constitui-se em estudo, realizado em escala de laboratório, relativo à produção de fertilizante fosfatado do tipo termofosfato magnesiano fundido utilizando as seguintes matérias-primas: concentrado fosfático de Catalão (GO), serpentinito e quartzito. O trabalho visa verificar a influência das seguintes variáveis básicas de processo sobre a estrutura e propriedade do produto: - composição química da mistura de matérias-primas alimentada ao forno de fusão; - temperatura de processamento dessa mistura, na etapa de fusão; - velocidade de resfriamento do produto à saída do forno de fusão. As condições necessárias para obtenção de produtos com alta disponibilidade de fósforo aos vegetais são discutidas, com base nos resultados obtidos. Conforme é mostrado, o principal fator responsável pela disponibilidade do fósforo contido no produto é a quantidade de cristais de fluorapatita presentes, os quais provem do concentrado fosfático. Esses cristais formam-se e aumentam de dimensões durante o resfriamento do produto, ao sair do forno. A velocidade de cristalização aumenta com o aumento do teor de PO, além de ser maior quando não é utilizado quartzito na mistura de matérias-primas. Porém, o produto pode ficar saturado em sílica quando se utiliza grande quantidade de quartzito na mistura, sem haver efeito positivo sobre a solubilidade do fósforo. Quando o produto contém 22% de PO a cristalização intensifica-se de tal forma que é necessário fundir a mistura a temperatura mais alta que a normal e resfriar rapidamente o produto para minimizar a quantidade de cristais presentes.The work described in the present text, originated from the creation of a research and development area on processes for production of fertilizers using thermal treatment by the Pertilizaers Research Center (CEFER) of IPT Technological Research Institute of the State of São Paulo, Brazil. That area is part of a program directed to studying the utilization of Brazilian natural resources in the production of fertilizers which are suited for use under the existing conditions in the country. Therefore, the author directs sincere thanks to the direction of IPT and CEFER for the incentive received. Grateful aknowledgements are directed to some persons who played an assential role in the development of the work and are listed bellow. Prof. Dr. Jumpei Ando, from Chuo University, Tokyo, for orientating the work, from the development of the methodology, planning and execution of tests, to the discussion of results. Kazuo Takemura, Fumiaki Matsishima and Masato Watanabe, from Chuo University, Tokyo, for their assistance in the fusion tests, as well as in many examinations made in the products and in discussing the results. Jairo de SantAnna Tadeu and Eleno de Paula Rodrigues, from the Mines and Applied Geology Division of IPT, for their collaboration in examinating and photographing samples by petrographic microscope. Antonio Carlos Joaquim, from the Metallurgy Division of IPT, for his assistance in examinating and photographing samples by scanning electron microscope. Paulo Mori and André Luis Moreira da Silva, from the Mines and Applied Geology Division of IPT, for their assistance in examinating samples by X-ray diffraction. - - Aparecida Escanhuela Russo, from CEPER, IPT, for her attention, efficiency and patience during typing and assembling the final text. People from CEPER, IPT, for their incentive and assistance during thedevelopment of the work. Special thanks are directed to Prof. Gil Anderi da Silva, for the incentive received through his role as advisor for the work here described
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
Study on the thermal degradation of emulsions via UV-VIS spectroscopy applied to metalworking fluids.
No full textO monitoramento de emulsões utilizadas na indústria metalmecânica compõe uma importante atividade para o controle da qualidade das peças trabalhadas, proporcionando também o aumento da vida útil de ferramentas e maquinários utilizados neste setor através da lubrificação e refrigeração da região de corte. Em grande parte dos casos, estas emulsões são preparadas pela diluição de um fluido de corte em meio aquoso, constituindo assim um conjunto de gotículas estabilizadas em um meio contínuo devido à presença de compostos emulsificantes, estando constantemente sujeitas a ciclos de aquecimento e resfriamento durante os processos de usinagem. Apesar do acompanhamento deste material ser realizado através de análises periódicas usuais, não há um método eficiente estabelecido para verificar sua qualidade em tempo real e em linha de processo. Neste contexto, torna-se possível aplicar técnicas relacionadas à espectroscopia UV-Vis para se obterem informações sobre a estabilidade destes sistemas, correlacionando intensidades de espalhamento de luz com as dimensões das gotas presentes no meio. Dessa forma, tornou-se possível o estudo da desestabilização térmica de emulsões de um fluido de corte comercial, a qual mostrou-se, através do acompanhamento do cálculo do expoente do comprimento de onda, dependente do tempo de exposição ao aquecimento e de sua temperatura média temporal, não sendo influenciada pela perda de meio contínuo por processos evaporativos ou sua posterior reposição. Também se verificou que parâmetros típicos do processo de preparo de emulsões, como a temperatura do meio dispersante e o tempo de repouso do fluido de corte sobre a superfície do mesmo, apresentam fundamental importância para a definição do tamanho médio de gota inicial destes sistemas, o que forneceu evidência da possibilidade de se relacionar a área sob espectros de extinção de luz com tamanhos médios de gota.The monitoring of emulsions used in the metal-mechanical industry comprise an important activity to the quality control of the products manufectured, also providing an increase in the working life of the tools and machinery employed in this sector through the lubrication and refrigeration of the cutting zone. In the majority of cases, these emulsions are prepared diluting a metalworking fluid in an aqueous media, constituting a collection of particles stabilized by emulsifiers and undergoing heating and cooling cycles during metalworking processes. Currently, monitoring routines are based on regular analyses of samples taken from the process fluid, and an effective in-line method is not available to monitor emulsion quality in real time. In this context, it is possible to apply techniques related to UV-Vis spectrocopy in order to obtain information concerning the stability of those systems, correlating light scattering intensities to the droplet dimensions. In this study, it was possible to investigate the thermal destabilisation of a commercial metalworking fluid emulsion, which showed, through the evaluation of the wavelength exponent, to be dependant on the exposure time to heating and its time-averaged temperature. It was also noted that the loss of continuous phase by evaporation and its reposition do not affect the emulsion stability. Moreover, it was observed that important emulsion preparation parameters, such as continuous phase temperature and the time span between the addition of the metalworking fluid on the water surface and the stirring, have fundamental roles in defining the initial average droplet size, which made possible to correlate the area under the light extinction spectra with average droplet sizes
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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No full textNo presente trabalho, o processo foto-Fenton para oxidação de solução aquosa de fenol foi investigado utilizando sistemas de reatores fotoquímicos com fonte de luz artificial e solar. Experimentos, em escala de laboratório, foram conduzidos em reatores fotoquímicos anulares com lâmpada de vapor de mercúrio de média pressão (Ace-Hanovia 7825-34 e Heraeus TQ 150), reator tubular com coletor parabólico (PTR), e reator do tipo filme descendente (TFFBR). Os resultados demonstraram a viabilidade aplicação do processo foto-Fenton para o tratamento de efluentes contendo solução aquosa de fenol. Conversões de carbono orgânico total (COT) de 90% foram alcançadas em 3 horas de irradiação solar, mesmo em dias nublados. Experimentos realizados sob diferentes condições de radiação solar sugeriram uma dependência aproximadamente linear entre o COT e a energia solar acumulada que alcança o sistema. Modelos baseados em redes neurais foram desenvolvidos para a cinética do processo. A partir da avaliação dos parâmetros da rede, 6 neurônios na camada oculta foram suficientes para um bom ajuste dos dados e para descrever o processo de oxidação de fenol. Modelos baseados em redes neurais (\"oft sensor\") foram desenvolvidos para o monitoramento do processo. O objetivo do \"soft sensor\" é inferir valores de COT a partir de medidas de espectro de absorção. Assim, torna-se possível implementar monitoramentos on-line do processo, reduzindo o tempo e o custo de uma análise convencional de carbono orgânico total.In this work, the photo-Fenton oxidation of phenol in aqueous solutions has been investigated using solar and artificial light sources. Laboratory-scale experiments were carried out in two different solar reactors configurations, a parabolic through reactor (PTR) and a thin-film reactor, and in an annular photochemical reactor using different medium pressure mercury lamps (Ace-Hanovia 7825-34 and Heraeus TQ 150). The results indicate that the photo-Fenton process is an effective treatment for industrial wastewater containing phenol. Until 90% of the total organic carbon content of the initial phenol solution could be converted in inorganic carbon within 4 hours of solar irradiation, even in cloudy days. Experiments under different insolation conditions suggest a direct linear dependence of the organic carbon removal on the accumulated sunlight energy reaching the system. A model based on artificial neural networks has been developed for fitting the experimental of photo-Fenton process. The model with 6 neurons in the hidden layer can describe the evolution of the pollutant concentration in the complex photo-Fenton reaction. The neural network-based soft sensor for estimating the TOC in the wastewater treatment process by photodegradation has resulted in an efficient and accurate means for process monitoring. Since the measurement is based on light spectroscopy data, it is possible to implement on-line and in-line process monitoring in a much simpler andeconomical way than by conventional methods like TOC analysis, for example. Due to the reduced sample handling steps involved, less dispersion was observed in the estimated TOC values. Besides the lower cost and work involved, the shorter time to obtain the TOC concentration has enabled the operating staff to act on the process
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No full textNeste trabalho se ajustou um modelo de redes neurais para a predição do comportamento de tensoativos como emulsionantes de misturas de solventes orgânicos e compostos orgânicos com efeito pesticida. O modelo desenvolvido é capaz de prever o valor da leitura de quebra de emulsão, uma medida da estabilidade destes sistemas. Os ingredientes ativos foram descritos por seis parâmetros físico-químicos, coeficiente de partição octanol/água, volume molar, índice de refração, densidade, parâmetro de solubilidade de Hildebrand e constante de Henry. Os solventes e suas misturas podem ser representados por três parâmetros físico-químicos, densidade, parâmetro de solubilidade de Hildebrand e tensão superficial. Completam as variáveis de entrada a dureza da água de teste, a concentração de ingrediente ativo e de cada um dos tensoativos. Como variável de saída utilizou-se a porcentagem de formação de creme após dispersão do concentrado emulsionável em água. Com esta configuração a rede neural treinada foi capaz de prever a leitura de quebra de emulsão. Em uma outra abordagem tentou-se a substituição dos tensoativos não-iônicos pelo número médio de HLB resultando-se em perda de precisão do modelo para a previsão da leitura de quebra de emulsão. No entanto, com esta abordagem o modelo é capaz de discriminar as regiões de estabilidade e instabilidade de emulsão. Através deste modelo podem-se construir diagramas de fase e determinar a formulação ótima para se emulsionar umadeterminada mistura de solvente e princípio ativo, reduzindo-se o tempo de desenvolvimento de formulações, com conseqüente diminuição da quantidade de efluentes gerados e redução da exposição dos técnicos aos ingredientes ativos.In this work a neural network based model was developed in order to predict emulsification properties of mixtures of surfactants, organic solvents and organic compounds with pesticidal action. The model is able to predict the emulsion brake reading, a measure of the system\'s stability. Six physical-chemical parameters were used as descriptors for the active ingredients, Octanol / water partition coefficient, molar volume, refractive index, density, Hildebrand solubility parameter and Henry constant. The solvents and their mixtures can be described by their density, Hildebrand solubility parameter and surface tension. Other input variables include water hardness, active ingredient and surfactant concentrations. The output variable was the volume percentage of cream formation after dispersion of the emulsifiable concentrate in water, which could be predicted by the trained neural network. In another approach the non-ionic surfactants were resumed by their average HLB number. This resulted in loss of information fed to the neural network which predicted poorer estimates for the cream formation. Nevertheless in this approach the neural network can discriminate between emulsion stability and instability regions. The work provided a tool to build phase diagrams that can be used to determine the optimum surfactant mixture that will emulsify a specific solvent and active ingredient combination thus reducing the time needed for the development of such formulations andreducing formulators\' exposure and effluent production
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