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421.
We present a model for calculating the friction at the head/tape interface as a function of wrap angle, tape speed, tension and head dimensions. The model is based on the Euler–Bernoulli beam equation and the Reynolds equation. Several refinements relative to previous implementations are introduced: specifically a multi-coefficient slip-flow correction is implemented to deal with the reduction of spacing, the skiving-edge profile is modeled using interferometer microscope measurements to account for edge rounding, and the tension asymmetry due to friction is accounted for. Results from the model are compared with experimental measurements of friction versus wrap angle and tape velocity. The model and the experiment show excellent agreement under the range of conditions studied. 相似文献
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Aleksi Eskelinen Alexey Zakharov Sirkka‐Liisa Jämsä‐Jounela Jonathan Hearle 《American Institute of Chemical Engineers》2015,61(11):3683-3698
A dynamic model of a multiple hearth kaolin calciner has been developed and is presented in this article. This model describes the physical‐chemical phenomena taking place in the six furnace parts: the solid phase, gas phase, walls, cooling air, rabble arms, and the central shaft. The solid phase movement, in particular, is described by a novel mixing model. The mixing model divides the solid bed in a hearth into volumes and the distribution of their contents, after one full central shaft rotation, is identified by the pilot experiments. First, the model is validated by the industrial data, and then the dynamics of the multiple hearth furnace is studied by introducing step changes to the three manipulated variables: the feed rate, and the gas, and air flows supplied. The responses of the gas phase temperature and solid bed component profiles are analysed and the results are discussed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3683–3698, 2015 相似文献
425.
Marika Vespa Erich Wieland Rainer Dähn Barbara Lothenbach 《Journal of the American Ceramic Society》2015,98(7):2286-2294
Current developments in cement chemistry increasingly rely on predictive thermodynamic modeling of the phase composition in cementitious composites with the aim of linking the performance of the material with the phase composition of the material. This approach requires identification of the cement phases that form in hydrating cementitious materials using standard techniques, such as X‐ray diffraction (XRD) and thermal analysis (DTA, TGA), but also state‐of‐the‐art synchrotron‐based techniques, in particular for those cases in which the signals of solid solutions overlap in XRD and TGA measurements. In this study, two ordinary Portland cements, with different chemical compositions and subject to different hydration times (~10, ~50 yr), were investigated aiming at identifying the most stable Fe‐containing cement phase in the cement pastes. The Fe‐containing cement phases and their solid solutions with the Al analogues in the complex cement matrix were analyzed with X‐ray absorption spectroscopy, indicating the formation of a mixed Fe–Al siliceous hydrogarnet as the major Fe‐containing phase. The presence of this phase after long hydration periods and upon selective dissolution of the pastes further indicates that, independent of the chemical compositions of cements, formation of the mixed Fe–Al siliceous hydrogarnet is thermodynamically favored in aged pastes, which is supported by published thermodynamic calculations. 相似文献
426.
Manuel Längauer Keyan Liu Christian Kneidinger Gernot Schaffler Bianca Purgleitner Gernot Zitzenbacher 《应用聚合物科学杂志》2015,132(13)
Extrusion technology is one of the most prominent methods for processing polymers. The shape of polymer pellets plays an important role in conveying solid material through the extruder and thus directly influences the mass flow rate. In the course of this article, the influence of the pellet shape of a polypropylene homopolymer on the processing conditions using a smooth barrel single‐screw extruder is evaluated. Especially the mass flow rate, the melt temperature, and the pressure build up in the barrel are investigated. It can be shown that processing long cylindrical pellets leads to a higher mass flow rate than comparable experiments with virgin pellets or short cylinders. Additionally, screw cool and pull‐out tests, measurements of the external coefficient of friction as well as the bulk density of the different pellet geometries are performed. The interaction of the screw geometry and the pellet shape is found to have the biggest influence. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41716. 相似文献
427.
Heinz E. May T. Born D. Zieger G. Anders S. Zakosarenko V. Meyer H.-G. Schäffel C. 《Journal of Infrared, Millimeter and Terahertz Waves》2015,36(10):879-895
Journal of Infrared, Millimeter, and Terahertz Waves - Passive submillimeter-wave imaging is a concept that has been in the focus of interest as a promising technology for personal security... 相似文献
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Dr. Ralf Bandorf Stefan Waschke Dr. Michael Vergöhl Prof. Dr.‐Ing. Guido Grundmeier Prof. Dr. Günter Bräuer 《真空研究与实践》2015,27(4):18-23
Direct metallization of plastics by high powerimpulse magnetron sputtering Even if polymers are today industrially used for decades the direct metallization of plastics is still a hot topic for research and development. Especially in light of the ban of hexavalent chromium an increasing demand for well‐adhering plastic metallization arises. High power impulse magnetron sputtering HIPIMS is a recent technology that can offer a high potential for successfully solving this challenge. This article focuses on the direct metallization of plastics by HIPIMS. In the frame of the investigations any pretreatment was ignored and the different polymers were directly under vacuum metallized. Compared to conventional mid‐frequency sputtering a significant improvement in adhesion was shown for different polymers. In detail the metallization of Plexiglas (PMMA) was investigated, since this polymer is highly challenging with respect to plasma processes. Due to the UV radiation damage of PMMA during plasma deposition direct metallization is usually not possible. Using ionized deposition it was possible to directly metallize the substrates with excellent adhering films without any interface layers or special pretreatments. The characterization of the substrate‐coating interface showed that for the well adhering films a cohesive fracture, i.e. a fracture within the polymer occurred. 相似文献
430.
Plasmonic Absorbers: A Switchable Mid‐Infrared Plasmonic Perfect Absorber with Multispectral Thermal Imaging Capability (Adv. Mater. 31/2015)
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