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991.
Weon Gyu Shin Jing Wang Michael Mertler Bernd Sachweh Heinz Fissan David Y.H. Pui 《Journal of aerosol science》2010,41(11):975-986
We investigated the effect of particle morphology on unipolar diffusion charging of nanoparticle agglomerates consisting of multiple primary spheres. In the unipolar diffusion charging of non-spherical agglomerates, geometric surface area and electrical capacitance of particles, which are related to particle morphology, are known as important parameters to determine mean charge per particle. From mobility analysis we found that the geometric surface area of chain-like agglomerates is only larger than that of spherical particles with the same mobility diameter for mobility size range below dm=80 nm. We estimated the electrical capacitance of agglomerates with a newly developed model based on electrostatics and mobility theories. The results show that the electrical capacitance of chain-like agglomerates becomes significantly larger compared to that of spheres with the same mobility diameter as particles become larger. Our analysis results indicate that loose agglomerates have larger mean charge per particle compared to compact particles with the same mobility diameter because the electrical capacitance of agglomerates becomes larger as particle morphology becomes looser. Our experimental data show that mean charge per particle for silver agglomerates is larger than that for fully coalesced silver spheres with the same mobility diameter as agglomerates by about 24%. The experimental data is in good agreement with estimates of mean charge per particle for silver agglomerates. 相似文献
992.
Heinz Peeken 《Forschung im Ingenieurwesen》1966,32(2):63-65
Zusammenfassung Zum Berechnen von Kugelgleitlagern vorliegende, theoretisch hergeleitete Beziehungen werden mit Messungen an einem Lager dieser
Bauart auf einem Lagerprüfstand des Max-Planck-Instituts für Reibungsforschung, G?ttingen, verglichen. Der Vergleich best?tigt
die theoretisch erarbeiteten Gleichungen; die übereinstimmung ist gut.
Mitteilung aus der Abteilung Reibungsforschung am Max-Planck-Institut für Str?mungsforschung, G?ttingen. 相似文献
993.
Mario Keplinger Dominik Kriegner Julian Stangl Thomas Ma˚rtensson Bernhard Mandl Eugen Wintersberger Günther Bauer 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(3-4):316-319
Recent investigations of core–shell nanowires using synchrotron radiation techniques deduced the average structural parameters of heterostructure core–shell nanowires. Here, we report on first results and discuss the problems arising when measuring such complex nanostructures by using nanofocusing X-ray techniques. InAs/InAsP core–shell nanowires exhibit a certain bending, the origin of which is described using finite element simulations assuming a displacement of the core, and a gradient in the chemical composition of the wire’s shell. 相似文献
994.
995.
Powders and grains exhibit unpredictable jamming-to-flow transitions that manifest themselves on geophysical scales in catastrophic slip events such as landslides and earthquakes, and on laboratory/industrial scales in profound processing difficulties. Over the past few years, insight into these transitions has been provided by new evidence that slip events may be accompanied, or even preceded, by electrical effects. In the present work, we quantify the correlation between slip and the separation of electrical charges, using an archetypal granular material: photoelastic polymers. We measure a strong correlation between material displacement, acoustic emissions, and voltage. We find that the generation of voltage is associated with surface, rather than bulk properties of the granular materials. While voltage precursors are only occasionally observed in this system, there is some asymmetry in the cross-correlation between the slip and voltage signals that indicates differences between the pre- and post-slip dynamics. 相似文献
996.
997.
INES – An Interface Between Experiments and Simulation to Support the Development of Robust Process Designs
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Norbert Asprion Regina Benfer Sergej Blagov Roger Böttcher Michael Bortz Maksym Berezhnyi Jakob Burger Erik von Harbou Karl‐Heinz Küfer Hans Hasse 《化学,工程师,技术》2015,87(12):1810-1825
The development of chemical processes is based on both experiments and process simulations. Data evaluation and reconciliation, model development and validation, and design of experiments are essential steps in this procedure. The different tools and approaches available are usually not supported in an integrated way in the process developer's workflow. Therefore, a framework for process design was created and integrated in a tool box which supports process design comprehensively. It contains methods for data selection and reconciliation, sensitivity analysis, model validation and model adjustment. 相似文献
998.
Erich Bauer Zhongzhi Fu Sihong Liu 《Frontiers of Architecture and Civil Engineering in China》2010,4(1):78-91
The wetting deformation of weathered rockfill materials has been attracting growing attention from both engineers and scientists.
The importance of realistic predictions of wetting deformations for high earth and rockfill dams is a strong motivation to
establish a suitable constitutive model. Recently, the hypoplastic constitutive model by Gudehus and Bauer was extended by
introducing solid hardness depending on the state of weathering. The extended model takes into account the influence of the
current density, the effective stress state, the rate of deformation, and the time dependent process of degradation of the
solid hardness. In the present paper, the performance of this model is evaluated by comparing numerical simulations with experiments
obtained from a water sensitive rockfill material. In particular, triaxial compression paths and creep deformation under deviatoric
stress states are considered. Finally, the constitutive model proposed is used to study the influence of a degradation of
the solid hardness on the long term behavior of a hypothetical fill dam. 相似文献
999.
Alex Bauer Chaojie Song Rob Hui Laure Chevallier Jacques Rozière 《Electrochimica acta》2010,55(28):8365-8370
The electrochemical stability of Pt deposited on mesoporous carbon, which was either applied in its unmodified state or coated with 20 wt% TiO2, was investigated by cyclic voltammetry in N2 purged 0.5 M sulfuric acid. XRD analysis revealed that TiO2 was present in the anatase phase. The mean Pt particle diameter was ∼6 and ∼4 nm for mesoporous carbon with and without TiO2, respectively. Pt supported on TiO2 modified substrates was more stable than Pt supported on conventional mesoporous carbon when subjected to 1000 cycles in the potential range from 0.05 to 1.25 V vs. RHE. This was evident from the observation that the support with TiO2 retained ∼53% of the electrochemically active surface area relative to the state observed after 100 cycles, whereas ∼33% of the active area remained in the case without TiO2. The oxygen reduction mass activity was identical for both fresh samples (i.e., ). After 1000 cycles the mass activity decreased to for the case without TiO2, whereas with TiO2 the deactivation was minor; i.e., the mass activity after 1000 cycles was . 相似文献
1000.
A. S. Aric A. Di Blasi G. Brunaccini F. Sergi G. Dispenza L. Andaloro M. Ferraro V. Antonucci P. Asher S. Buche D. Fongalland G. A. Hards J. D. B. Sharman A. Bayer G. Heinz N. Zandon R. Zuber M. Gebert M. Corasaniti A. Ghielmi D. J. Jones 《Fuel Cells》2010,10(6):1013-1023
Polymer electrolyte fuel cell stacks assembled with Johnson Matthey Fuel Cells and SolviCore MEAs based on the Aquivion™ E79‐03S short‐side chain (SSC), chemically stabilised perfluorosulphonic acid membrane developed by Solvay Solexis were investigated at CNR‐ITAE in the EU Sixth Framework ‘Autobrane' project. Electrochemical experiments in fuel cell short stacks were performed under practical automotive operating conditions at pressures of 1–1.5 bar abs. over a wide temperature range, up to 130 °C, with varying levels of humidity (down to 18% R. H.). The stacks using large area (360 cm2) MEAs showed elevated performance in the temperature range from ambient to 100 °C (cell power density in the range of 600–700 mWcm–2) with a moderate decrease above 100 °C. The performances and electrical efficiencies achieved at 110 °C (cell power density of about 400 mWcm–2 at an average cell voltage of about 0.5–0.6 V) are promising for automotive applications. Duty‐cycle and steady‐state galvanostatic experiments showed excellent stack stability for operation at high temperature. A performance comparison of AquivionTM and NafionTM‐based MEAs under practical operating conditions showed a significantly better capability for the Solvay Solexis membrane to sustain high temperature operation. 相似文献