322,972 research outputs found
Mikroaaltoavusteisen MP-AES-menetelmän soveltuvuus Hugger-murskaimella tuotettujen mineraalipartikkeleiden analysoimiseen
No full textTiivistelmä. Maapallon raaka-ainevarojen kestävään hyödyntämiseen tarvitaan uusia ja innovatiivisia menetelmiä. Kaivos- ja rikastusteollisuudessa käytetyt malmien hienonnusmenetelmät kuluttavat suurimman osan energiasta ja tuottavat eniten jätteitä metallien ja mineraalien arvoketjussa. Myös hienonnustuotteiden ja -jätteiden kemialliset analyysit kuluttavat arvokkaita luonnonvaroja reagenssien ja suojakaasujen muodossa.
Tässä opinnäytetyössä tarkastellaan uuden ja innovatiivisen Hugger-murskauksen toimintaperiaatetta. Hugger-murskaus perustuu ”free crushing” -ilmiöön, jossa malminkappaleiden hienonnus tapahtuu niiden sisältämien mineraalien luonnollisia raerajoja pitkin. Tavoitteena on tuottaa mahdollisimman puhtaita mineraalipartikkeleita kuluttamalla mahdollisimman vähän energiaa, vettä ja kemikaaleja. Hugger-murskaustekniikka on nykyisin aktiivisen menetelmäkehityksen kohteena, mutta sen toimintaperiaatteen taustalla olevat fysikaaliset ilmiöt on tunnettu jo 1950-luvulta asti.
Tässä opinnäytetyössä tarkastellaan myös mikroaaltoavusteisen hajotuksen, mikroaaltoplasma-atomiemissiospektrometrin (MP-AES) ja röntgenfluoresenssi-spektroskopian (XRF) käyttöä malmien hienonnustuotteiden analyyseissä. Nämä hajotus- ja analyysimenetelmät ovat paitsi nopeita myös edullisia, sillä ne kuluttavat mahdollisimman vähän hajotus- ja analyysireagensseja. Lisäksi MP-AES-menetelmässä käytetyn laitekohtaisen typpigeneraattorin tuottama typpikaasu tekee siitä huomattavasti edullisemman vaihtoehdon muihin plasmaemissiotekniikoihin verrattuna. Opinnäytetyössä osoitetaan edellä mainittujen Hugger-murskaus-, mikroaaltohajotus-, XRF- ja MP-AES-tekniikoiden soveltuvuus rinnakkaiskäyttöön.Applicability of microwave-assisted MP-AES method for the analysis of mineral particles produced by the Hugger crusher. Abstract. New and innovative methods are needed for the sustainable utilisation of the earth’s raw materials. The ore grinding methods used in the mining and beneficiation industry consume most of the energy and produce the most waste in the value chain of metals and minerals. Chemical analyses of comminution products and waste also consume valuable natural resources in the form of reagents and shielding gases.
This thesis examines the operating principle of the new and innovative Hugger crushing. Hugger crushing is based on the "free crushing" phenomenon, where ore bodies are crushed along the natural grain boundaries of the minerals they contain. The goal is to produce the purest possible mineral particles by consuming as little energy, water, and chemicals as possible. Hugger crushing technology is currently the subject of active method development, but the physical phenomena underlying its operating principle have been known since the 1950s.
This thesis also examines the use of microwave-assisted digestion, microwave plasmaatomic emission spectrometer (MP-AES) and X-ray fluorescence spectroscopy (XRF) in the analysis of ore crushing products. These digestion and analysis methods are not only fast but also inexpensive, as they consume as little digestion and analysis reagents as possible. In addition, the nitrogen gas produced by the device-specific nitrogen generator used in the MP-AES method makes it a significantly more affordable alternative compared to other plasma emission techniques. In this thesis, the suitability of the Hugger crushing, microwave digestion, MP-AES, and XRF techniques for parallel use is demonstrate
Uwe Sander / Friederike von Gross / Kai-Uwe Hugger (Hrsg.): Handbuch Medienpädagogik. Wiesbaden: VS Verlag für Sozialwissenschaften 2008 (602 S.) [Rezension]
No full textRezension von: Uwe Sander / Friederike von Gross / Kai-Uwe Hugger (Hrsg.): Handbuch Medienpädagogik. Wiesbaden: VS Verlag für Sozialwissenschaften 2008 (602 S.; ISBN 978-3-531-15016-1; 49,90 EUR)
Identitätskonstruktionen in digitalen Welten
No full textGanguin S, Sander U. Identitätskonstruktionen in digitalen Welten. In: Sander U, von Gross F, Hugger K-U, eds. Handbuch Medienpädagogik. Wiesbaden: VS Verlag; 2008: 422-427
Kritisch-emanzipative Medienpädagogik
No full textGanguin S, Sander U. Kritisch-emanzipative Medienpädagogik. In: Sander U, von Gross F, Hugger K-U, eds. Handbuch Medienpädagogik. Wiesbaden: VS Verlag; 2008: 61-65
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
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
Quantized Magnetic Confinement in Quantum Wires
No full textBallistic quantum wires are exposed to longitudinal profiles of perpendicular magnetic fields composed of a spike and a homogeneous part. An asymmetric magnetoconductance peak as a function of the homogeneous magnetic field is found, comprising quantized conductance steps in the interval where the homogeneous magnetic field and the magnetic barrier have identical polarities, and a characteristic shoulder with several resonances in the interval of opposite polarities. The observations are interpreted in terms of inhomogeneous diamagnetic shifts of the quantum wire modes leading to magnetic confinement.Original Publication:A Tarasov, S Hugger, Hengyi Xu, M Cerchez, T Heinzel, Igor Zozoulenko, U Gasser-Szerer, D Reuter and A D Wieck, Quantized Magnetic Confinement in Quantum Wires, 2010, PHYSICAL REVIEW LETTERS, (104), 18, 186801.http://dx.doi.org/10.1103/PhysRevLett.104.186801Copyright: American Physical Societyhttp://www.aps.org
‘I’m not a tree hugger, I’m just like you’:changing perceptions of sustainable lifestyles
No full textFor many in the Western world, there is increasing recognition of the fundamentally unsustainable nature of everyday actions and modes of consumption that form part of normal life. Some individuals attempt to challenge current ways of consuming and living in order to address these underlying issues. However, these efforts often continue to be positioned as unusual or unconventional, meaning that adopting sustainable lifestyles may be subject to wider negative perceptions. At the same time, some forms of action towards sustainable ways of living are becoming increasingly normalised as more people make moves towards sustainable consumption. Drawing on data from the qualitative longitudinal Energy Biographies project, we consider the experiences of those who describe their efforts to live sustainably, the relationship between sustainability and normality, and the implications of this in a context of fundamental trends towards unsustainable social systems
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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