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Nils-OlofNilvebrant,Niklas Garoff,Christer Fellers 한국펄프·종이공학회 1999 한국펄프종이학회 기타 간행물 Vol.- No.-
Friction was measured on filter paper sheets impregnated with model compounds representing wood extractives using an apparatus based on the horizontal plane principle. The best lubrication of paper surfaces was achieved when they were completely separated by a densely packed film of saturated long-chain amphophilic molecules, such as fatty acids. The fatty acids adsorbed with their polar ends on the paper surface, causing their hydrocarbon chains to be orientated perpendi-cularly to the paper surface. The saturated C 18-acid, stearic acid, was an efficient lubricator for paper surfaces. The introduction of a double bond in stearic acid eliminated its lubricating ability. The spatial length of the lubricating fatty acid thereby decreases from 24 A to II A. However the trans-isomer of oleic acid, elaidic acid, had the ability to lower friction due to an increased spatial length of the fatty acid. Both the spatial length of the hydrocarbon chain and the number of lubricating chains may be of importance for the paper-ta-paper friction caused by wood extractives. A hydrophilic head-group in the wood extractive and an ordered molecular layer of lubricating molecules seems also to be prerequisites for efficient lubrication. A chemical weak boundary layer between the paper sheets was suggested to cause the low friction when long chain saturated fatty acids were deposited on paper.
Diego A. Luna Bazaldua,이영선,Bryan Keller,Lauren Fellers 서울대학교 교육연구소 2017 Asia Pacific Education Review Vol.18 No.4
The performance of various classical test theory (CTT) item discrimination estimators has been compared in the literature using both empirical and simulated data, resulting in mixed results regarding the preference of some discrimination estimators over others. This study analyzes the performance of various item discrimination estimators in CTT: point-biserial correlation, point-biserial correlation with item excluded from the test total score, biserial correlation, phi coefficient splitting total score using the median, and discrimination index. For this study, data were generated from unidimensional logistic item response theory (IRT) models with one and two parameters. The factors considered in the study were test length, intervals for item difficulty and item discrimination parameters, as well as the composition of one or two groups of the examinees with specific ability distribution parameters. Results indicate that the biserial coefficient was most highly correlated with the IRT discrimination parameter across different simulation conditions. The degree of comparability among estimators and estimator invariance varied across conditions.
Feller, J. F.,Lu, J.,Zhang, K.,Kumar, B.,Castro, M.,Gatt, N.,Choi, H. J. Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.12
<P>For the first time vapour sensors were made by assembling multi-wall carbon nanotube (CNT) decorated poly(methyl methacrylate) microbeads (PMMAµB) by spray layer by layer (sLbL). This combination of materials and technique resulted in an original hierarchical architecture with a segregated network of CNT bridging PMMAµB. The chemo-resistive behaviour of these conductive polymer nanocomposite (CPC) sensors was studied in terms of sensitivity and selectivity towards standard volatile organic compounds (VOC), as well as quantitativity and reproducibility of responses <I>A</I><SUB>r</SUB> to methanol, water, toluene and chloroform. Results show that 3D sLbL assembly allows boosting CNT network sensitivity by a factor 2 and selectivity for methanol vapour by a factor of 5. Additionally CNT-PMMAµB sensors gave responses proportional to vapour molecules content that could easily be fitted by the Langmuir–Henry-clustering model. Such sensors are thus expected to be good candidates for implementation in electronic noses.</P> <P>Graphic Abstract</P><P>Vapour sensors with original hierarchical 3D conducting architecture from CNT decorated PMMAµ beads spraying layer by layer. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm03779f'> </P>
Language for Deep Learning: Cognitive Explorative Action Games for Teacher-Learner Interactions
( Sebastian Feller ) 서울대학교 인지과학연구소 2013 Journal of Cognitive Science Vol.14 No.4
This paper explores the design of what I call explorative action games for teacher-learner interactions. I argue that explorative actions games scaffold the learner`s re-representation of knowledge in ways that facilitate higher-level thinking and deep reasoning. With reference to Weigand`s (2010) Theory of Dialogic Action Games, I introduce the minimal form of the game, which consists of the explorative and the discovery speech act pair. Both speech acts are mutually related to each other. The explorative action game thereby revolves around knowledge re-representations in terms of Chi and Ohlsson`s (2005) types of changes with special emphasis on “greater complexity”, “higher level of abstraction”, and “shifted vantage point”. I illustrate explorative action games for these types and show how they are linked to deep learning and dialogic knowledge building.
QUIET-SUN INTENSITY CONTRASTS IN THE NEAR-ULTRAVIOLET AS MEASURED FROM SUNRISE
Hirzberger, J.,Feller, A.,Riethmü,ller, T. L.,Schü,ssler, M.,Borrero, J. M.,Afram, N.,Unruh, Y. C.,Berdyugina, S. V.,Gandorfer, A.,Solanki, S. K.,Barthol, P.,Bonet, J. A.,Martí,nez Pille IOP Publishing 2010 ASTROPHYSICAL JOURNAL LETTERS - Vol.723 No.2