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排序方式: 共有511条查询结果,搜索用时 15 毫秒
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Victor Gabriel Marian Dumitru Gabriel Gunter Knoll Salvatore Filippone 《Tribology Letters》2011,44(3):335-343
In this article, a laser partially textured thrust bearing is theoretically and experimentally analyzed. An adiabatic model
is developed in order to theoretically investigate the performances of the bearing. The bearing sample is partially textured
both in radial and circumferential direction using the laser texturing process. The performance of the bearing (fluid film
thickness and friction torque) is evaluated on a specially adapted test rig and the experimental results are compared with
the theoretical model. A good agreement is found between the theoretical model and the experimental data. Also a comparison
between a laser textured bearing and a bearing textured using the photolithographic method is presented. 相似文献
14.
This paper presents some of the theoretical predictions and experimental results for the steady-state characteristics of a gas-lubricated, pivoted-pad journal bearing of finite length. An analytical expression for the prediction of load-carrying capacity for these bearings is developed from numerical computer solutions. Sample calculations are presented to show how the theoretical data may be utilized in the design of an actual pivoted-pad bearing. Improvements over previous approximate theories are discussed. 相似文献
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Phase transition temperatures can be used for thermometer calibrations in accordance with the ITS-90. For this the thermometer is inserted into a fixed-point cell filled with a highly pure substance. While the substance is melting or freezing the temperature inside the cell remains almost constant and the thermometer measures a plateau in the temperature curve. From this plateau the phase transition temperature needs to be estimated for the calibration of the thermometer. This can be done using different mathematical methods, taking into account various systematic deviations as well as reproducibilities of the results depending on the chosen method, the fixed-point material’s purity and above all the amount of fixed-point material. Hence this article presents results from measurements in miniature fixed-point cells filled with zinc of various purities. The plateau curves were measured at different heating rates and comparatively analysed using five different estimation methods. 相似文献
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Dipl.-Ing. Gunter Gschwandtner Robert Galler Viktoria Wörgetter Franz Riepler Sylke Hilberg 《BHM Berg- und Hüttenm?nnische Monatshefte》2013,158(2):53-59
The assessment of the stability of underground structures is an interdisciplinary task which consists of geology, hydrogeology, surveying and geotechnical engineering. This paper gives an example of how these disciplines, their methods and the acquisition of data work together to create a complex three-dimensional computer-model of underground structures. It demonstrates, that especially the complex layout of old and “grown” underground structures cannot be represented accurately in two-dimensional analyses or models and provide no realistic results for stability investigations. Related to the stability of underground structures, a non-negligible factor is the influence of water, whether surface, rain or groundwater. The occurring leaching process of gypsum leads to a weakening of the surrounding rock which causes a strength reduction. This softening of the material must be considered in long-term simulations. The presented comprehensive approach tries to provide a possibility to predict the time-dependent occurrence of vulnerabilities in the rock mass and thus gives the possibility to install support measures in an early stage. 相似文献
19.
Klaus Timmel Sven Eckert Gunter Gerbeth 《Metallurgical and Materials Transactions B》2011,42(1):68-80
This article describes laboratory experiments aimed at investigations of flow structures and related transport processes in
the continuous-casting mold under the influence of an external direct current (DC) magnetic field. The main value of cold
metal laboratory experiments consists in the capabilities to obtain quantitative flow measurements with a reasonable spatial
and temporal resolution. The experimental results presented here were obtained using a physical model operating with the room-temperature
alloy GaInSn. According to the concept of the electromagnetic brake, the impact of a DC magnetic field on the outlet flow
from the submerged entry nozzle (SEN) has been studied up to Hartmann numbers of approximately 400. The effect of the magnetic
field on the flow structure turned out to be complex. The flow measurements do not manifest a general braking effect, which
would be expected as an overall damping of the flow velocity and the related fluctuations all over the mold volume. Variations
of the wall conductivity showed a striking impact on the resulting flow structures. The experiments provide a substantial
database for the validation of respective numerical simulations. 相似文献
20.
M. Bieberle E. Schleicher F. Fischer D. Koch H.-J. Menz H.-G. Mayer U. Hampel 《Flow Measurement and Instrumentation》2010,21(3):233-239
Electron beam x-ray tomography is an imaging technique, which can provide cross-sectional images of an object of interest with about 1 mm spatial resolution at frame rates of up to 10,000 frames per second. As a non-intrusive method it is especially suited for studying multiphase flows. For this purpose we devised an experimental limited-angle scan setup which utilizes linear beam deflection to generate radiographic projections. This setup was employed in the study of gas–liquid flow in an experimental flow loop operated at different liquid and gas flow rates. Electron-beam tomography images were compared with image data of a wire-mesh sensor. The latter is a fast but intrusive imaging device which is commonly used in gas–liquid flow imaging and achieves comparable frame rates but at lower spatial resolution. As a novelty we implemented a dual-plane limited-angle electron beam x-ray tomography which allows us to gain information about the phase velocities using cross-correlation data analysis. 相似文献