1,721,328 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Metallisulfidien saostuminen sinkkipitoisissa liuoksissa
No full textMetal sulfide precipitation has long been recognized as an efficient technique to reduce the levels of harmful metals in wastewater towards acceptable limits. Advantages of the method include fast reaction rates, good settling properties of the precipitates, and the extremely low solubilities of most metal sulfides. Unfortunately, implementing sulfide precipitation has its challenges also. For example, the low solubilities easily lead to extremely high supersaturation levels, which can make the process difficult to control. Another disadvantage is the toxicity of sulfide to humans and to the environment. Especially, the generation of hydrogen sulfide can be a concern in certain conditions. To design and operate a sulfide precipitation process in a safe and efficient manner, a good understanding of the phenomena underlying the process is required.
This thesis aims to provide a summary of the theories needed to build a useful conceptual model of the sulfide precipitation process, based on an extensive review of the current scientific literature on metal sulfide systems. The knowledge of these theoretical principles can aid the engineers designing and operating these processes to direct their attention to essential issues in the process. Unfortunately, space limitations require many important details to be left outside the discussion, but I have tried to include references to sources in which these details can be found.
The focus of the thesis is on the solution chemistry and thermodynamics governing sulfide precipitation. Special emphasis has been given to solubility phenomena and modelling of equilibrium systems. In addition, chemical dynamics of the process has been discussed. Thermodynamics provides the means to quantify supersaturation, predict which phases will be stable under given conditions, and predict the solubilities of these phases. All this information can be of enormous practical value but since the timescales of precipitation processes are relatively short, kinetics is also required to complete the image. For example, the rates of nucleation, crystal growth, and aggregation strongly affect the particle size of the obtained precipitates. Finally, modelling mass transfer inside the reactor accurately requires the incorporation of fluid mechanics. Only by combining thermodynamics, kinetics, and fluid mechanics, a complete image of the sulfide precipitation process can be obtained. It is obvious that building a quantitative model incorporating all these aspects can be an overwhelming task. Fortunately, in many cases, more straightforward approaches, that utilize simplifying assumptions, can still provide valuable information about the process.Metallien saostus sulfideina on tunnettu jo pitkään lupaavana ja potentiaalisesti tehokkaana menetelmänä haitallisten metallien poistamiseksi jätevedestä. Menetelmän etuja ovat nopeat reaktiot, saostumien hyvät laskeutumisominaisuudet sekä useimpien metallisulfidien erittäin alhaiset liukoisuudet. Sulfidisaostukseen liittyy kuitenkin myös omat hankaluutensa. Alhaisista liukoisuuksista seuraa, että liuoksista tulee helposti erittäin ylikylläisiä, mikä voi tehdä prosessista vaikeasti ohjattavan. Haittapuolena on myös sulfidikemikaalien myrkyllisyys ihmisille ja ympäristölle. Varsinkin myrkyllisen vetysulfidin kehittyminen voi olla suuri huolenaihe. Jotta sulfidisaostusprosessia voitaisiin turvallisesti ja tehokkaasti operoida, on ymmärrettävä prosessin taustalla piileviä ilmiöitä.
Tämän opinnäytetyön tarkoituksena on aihetta käsittelevään tieteelliseen kirjallisuuteen pohjautuen luoda katsaus teorioihin, jotka antavat työkalut luoda käyttökelpoinen käsitteellinen malli prosessista. Näiden periaatteiden tunteminen voi auttaa prosessin parissa työskenteleviä asiantuntijoita suuntaamaan huomionsa olennaisiin asioihin prosessissa. Valitettavasti paljon tärkeitä yksityiskohtia on jouduttu jättämään tarkastelun ulkopuolelle tilarajoitteista johtuen, mutta olen pyrkinyt sisällyttämään mahdollisimman kattavasti viitteitä lähteisiin, joista tarkempaa tietoa voi löytää.
Tarkastelun pääpaino on metallisulfidisysteemien termodynamiikassa ja erityisesti liukoisuuksien mallintamisessa, mutta myös prosessin dynamiikka ansaitsee osansa huomiosta. Termodynamiikka mahdollistaa esimerkiksi ylikylläisyyden kvantifioinnin sekä stabiilien faasien ja niiden liukoisuuksien ennustamisen. Kaikella tällä informaatiolla voi olla erittäin suuri käytännön arvo, mutta koska saostusprosessien viipymäajat ovat verrattain lyhyitä, myös kinetiikkaa tarvitaan viimeistelemään kokonaiskuva prosessista. Esimerkiksi ydintymisen, kiteenkasvun ja aggregaation nopeudet pitkälti määräävät saostuvien partikkelien kokojakauman. Reaktorissa tapahtuvan aineensiirron kuvaamiseksi tarvitaan lisäksi myös virtausmekaniikkaa. Sulfidisaostusprosessin täydelliseen kuvaamiseen vaaditaan siis termodynamiikan, kinetiikan ja virtausmekaniikan yhdistämistä. On selvää, että kaikki nämä aspektit huomioivan kvantitatiivisen mallin luominen voi olla ylivoimainen tehtävä, mutta monissa tapauksissa yksinkertaistavia oletuksia hyödyntävät suoraviivaisemmat lähestymistavatkin voivat antaa arvokasta tietoa prosessista
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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