1,720,983 research outputs found
Impact of laser cutting on iron loss in high speed machines
Full text linkIn electrical machines, most of the iron loss estimation in finite element modeling is based on Bertotti coefficients obtained from the corresponding data sheet. However, often a more exact estimation of coefficients for the laminated steel material is needed. Especially in the case of high speed machines (where iron loss has the highest contribution to the total loss), it is very difficult to estimate the iron loss variation as a result of laser cutting when just using data sheet information as input data in finite element analysis. Laser cutting impacts also the magnetic properties, in terms of magnetization curves at different frequencies, not only the core losses. In this paper, three different core materials of the same lamination steel are prepared to realize the estimation of the Berttotti loss coefficient when the material is subjected to high frequency and under the stress of laser cutting. Experimental analysis is performed to obtain more precise values of Bertotti coefficients at a high frequency range so that they can be utilized in iron loss estimation in a high speed machine (100 krpm maximum speed-1667 Hz) which is further shown as an application. Finally, it is shown how frequency domain iron loss results can be utilized for the time stepping iron loss analysis
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
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
Zanieczyszczenie gleby metalami ciężkimi i trwałymi zanieczyszczeniami organicznymi (WWA, PCB i HCB) na obszarze przybrzeżnym Västernorrland, Szwecja
No full textThis paper presents an experimental study on the leaching of heavy metals, toxic chemicals and persistent organic pollutants (POPs) – PAh, PCB and hCB – from soil dredged from the coastal area of Västernorrland in northern Sweden. The soil was stabilized with cement/slag. Samples were subjected to modified surface leaching and shake tests using technical standards of the Swedish Geotechnical Institute (SGI). The experiments were performed using different blends of binding agents (30/70, 50/50, 70/30) and binder quantities (120 and 150 kg/m3) to analyze their effects on leaching. Soil properties, tools, and workflow are described. Binders included Portland cement and ground granulated blast furnace slag (GGBFS). Samples were tested to evaluate the min/max contents of pollutants (μg/l) for heavy metals (As, Ba, Pb, Cd, Co, Cu, Cr, hg, Mn, Mo, ni, S, V, Zn) and the hydrocarbon fraction index in the excess water. The leaching of heavy metals and POPs was assessed in sediments after the addition of the binder. The comparison was made against the two mixes (cement/slag in 30/70% and high/low binder with low/high water ratio). The results showed that 70% slag decreases the leaching of heavy metals and POPs. The equilibrium concentrations of DOC and heavy metals at L/S 10 (μg/l) were measured during the shake experiments to compare their levels in the groundwater that was used as a leachate. The leached content was assessed at L/S 10 in the upscaling experiments using four samples for PAh, PCB and various fractions of hydrocarbons: C10–C40, C10–C12, C12–C16 and C35–C40. The shake test showed a decrease in the leaching of heavy metals and POP substances from the soil subjected to stabilization by a higher amount of slag added as a binder. A binder blend with 30% cement and 70% of GGBFS showed the best performance.Niniejszy artykuł przedstawia eksperymentalne badania dotyczące wymywania metali ciężkich, toksycznych chemikaliów i trwałych zanieczyszczeń organicznych (TZO): WWA, PCB i HCB z pobranej gleby na obszarze przybrzeżnym Västernorrland w północnej Szwecji. Gleba była stabilizowana cementem/żużlem. Próbki poddano zmodyfikowanym próbom wypłukiwania powierzchniowego i wstrząsom z zastosowaniem standardów technicznych Szwedzkiego Instytutu Geotechnicznego (SGI). Eksperymenty przeprowadzono przy użyciu różnych mieszanek środków wiążących (30/70, 50/50, 70/30) i ilości środka wiążącego (120 i 150 kg/m3) w celu przeanalizowania ich wpływu na ługowanie. Opisano właściwości gleby, narzędzia i przebieg pracy. Spoiwa obejmowały cement portlandzki i mielony granulowany żużel wielkopiecowy (GGBFS). Próbki zostały przetestowane w celu określenia min/max zawartości zanieczyszczeń (µg/l) dla metali ciężkich (As, Ba, Pb, Cd, Co, Cu, Cr, Hg, Mn, Mo, Ni, S, V, Zn) i wskaźnika frakcji węglowodorowej w nadmiarze wody. Wymywanie metali ciężkich i TZO oceniano w osadach po dodaniu lepiszcza. Porównania dokonano dla dwóch mieszanek (cement/żużel w 30/70% i spoiwo o wysokiej/niskiej zawartości z niskim/wysokim stosunkiem wody). Wyniki wykazały, że 70% żużel zmniejsza wymywanie metali ciężkich i TZO. Stężenia równowagowe DOC i metali ciężkich przy L/S 10 (μg/l) mierzono podczas eksperymentów z wytrząsaniem w celu porównania ich poziomów w wodzie gruntowej stosowanej jako odciek. Zawartość wyługowaną oszacowano na poziomie L/S 10 w eksperymencie upscalingu (zwiększenia skali) przy użyciu 4 próbek WWA, PCB i różnych frakcji węglowodorów: C10–C40, C10–C12, C12–C16 i C35–C40. Próba wstrząsowa wykazała zmniejszenie wymywania metali ciężkich i substancji TZO z gleby poddanej stabilizacji większą ilością żużla dodawanego jako spoiwo. Najlepszą wydajność wykazała mieszanka spoiwowa zawierająca 30% cementu i 70% GGBFS.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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
Geochemical tests to study the effects of cement ratio on potassium and TBT leaching and the pH of the marine sediments from the Kattegat Strait, Port of Gothenburg, Sweden
No full textCement is a key construction material in civil and geotechnical engineering. However, its application for stabilization of marine sediments needs further investigation. This paper tests the effects of varied amounts of Portland cement added to soil samples on the leaching of tributyltin (TBT) from the contaminated marine sediments and evaluates the pH level. Identifying the best combinations of Portland cement / slag / Cement Kiln Dust (CKD) for effective treatment of soil samples is a central challenge in marine geotechnical investigations with major implications for stabilization of dragged coastal sediments. The paper aims to test the TBT leaching as well as pH level and potassium (K) content in soil samples. Materials included marine sediments collected from the seabed of the Port of Gothenburg, Kattegat Strait, southwest Sweden. The meth- odology applied the existing specifications of the Swedish Institute for Standards (SIS) for geochemical tests of soil stabilized by Portland cement/slag/CKD. Leaching in soil samples was examined for 2.25, 9 and 36 days. Variations in the speed of decline of TBT leaching were noted depending on the ratio of Portland cement. The methodology follows the SIS instructions regarding the procedure of leaching tests: SS-EN 15863. Mixtures with pure Portland cement and cement / CKD gave pH values between 11.5–12 in the surface leaching experiments. Mixing of slag / CKD or slag lowered the pH range to 11–11.5 and 10–10.5, respectively. The leaching of TBT was affected by the changed amounts of seawater in the surface leaching experiments. The study shows that leaching reduces over time when the mobile fraction is being washed away and replaced by other leaching mechanisms and processes. Furthermore, in models in which leaching of TBT and potassium were assessed, there were, on average, changes in behaviour on the 9th day during the experiment time treatment and stabilization afterwards.SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe
Seismic velocity of P-waves to evaluate strength of stabilized soil for Svenska Cellulosa Aktiebolaget Biorefinery Östrand AB, Timrå
No full textEvaluating soil strength by geophysical methods using P-waves was undertaken in this study to assess the effects of changed binder ratios on stabilisation and compression characteristics. The materials included dredged sediments collected in the seabed of Timrå region, north Sweden. The Portland cement (Basement CEM II / A-V, SS EN 197-1) and Ground Granulated Blast Furnace Slag (GGBFS) were used as stabilisers. The experiments were performed on behalf of the Svenska Cellulosa Aktiebolaget (SCA) Biorefinery Östrand AB pulp mill. Quantity of binder included 150, 120 and 100 kg. The properties of soil were evaluated after 28, 42, 43, 70, 71 and 85 days of curing using applied geophysical methods of measuring the travel time of primary wave propagation. The P-waves were determined to evaluate the strength of stabilised soils. The results demonstrated variation of P-waves velocity depending on stabilising agent and curing time in various ratios: Low water / High binder (LW HB), High water / Low binder (HW LB) and percentage of agents (CEM II / A-V/GGBFS) as 30%/70%, 50%/50% and 70%/30%. The compression characteristics of soils were assessed using Uniaxial Compressive Strength (UCS). The P-wave velocities were higher for samples stabilized with LW HB compared to those with HW LB. The primary wave propagation increased over curing time for all stabilized mixes along with the increased UCS, which proves a tight correlation with the increased strength of soil solidified by the agents. Increased water ratio gives a lower strength by maintained amount of binder and vice versa.SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe
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