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111.
The numerical simulation of comparative elastohydrodynamic lubrication between axisymmetrical and 3D elastic approaches on the radial lip seals is presented in order to determine the 3D effect of the elastic aspect of the seal lip. Indeed, the consideration of 3D model in other words the circumferential variation of the lip elastic deformation indicated a difference in the deformation distribution of the lip compared to the axisymmetrical approach. Consequently, the results show that the presence of the circumferential variation of the seal lip deformation has a significant effect on the pumping rate values. 相似文献
112.
Do Hoon Kim Umme Farva Woo Sik Jung Eui Jung Kim Chinho Park 《Korean Journal of Chemical Engineering》2008,25(5):1184-1189
This paper reports an alternative method for the growth of GaN epitaxial layer on (0001) Al2O3 substrate by hot-wall vapor phase epitaxy technique. Tris (N,N-dimethyldithiocarbamato)-gallium (III), Ga(mDTC)3 was introduced as a precursor material for the seed layer formation in the growth of GaN. Optimal growth conditions with
seed layers formed by the Ga(mDTC)3 concentration of 0.047 mol/L were identified: Growth temperature was found to be 850 °C, and optimal distance between the
reactant outlet and substrate was determined to be 12.5 cm. Characterization results showed that this growth method produce
high-crystallinity GaN epitaxial layers at a relatively lower growth temperature compared to the existing growth techniques
and simplify the growth process. 相似文献
113.
A statistical study of the particle shape and size of pure V2O5 and TiO2, and samples of coprecipitated V2O5---TiO2 catalysts with different V/Ti ratios, has been performed. They were also characterized by XRD, EDAX, SEM and XPS. The results showed that pure vanadium pentoxide is compose by large square or needle-shaped particles, while pure titanium dioxide has small and rounded ones. VTiO samples presented an area and shape, depending on the V/Ti ratio.
These results and the spectroscopical characterization conducted to a particle model of the catalysts. Those VOTi samples with high V/Ti ratio would have large V2O5 crystals acting as support of a V/TiO2 solid solution. In contrast, those samples with a low V/Ti ratio, would have the solid solution supporting vanadium pentoxide crystals. 相似文献
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116.
James Rodgers Kaye Wolf Norm Willis Don Hamilton Ralph Ledbetter Curtis Stewart 《Color research and application》1994,19(5):322-331
A multiplant Quality Improvement Team [QIT] was firmed to develop and implement an evaluation program for various color measurement .systems as potential replacements for the then-current aging systems. The emphasis qf this article is the analytical methodology utilized to evaluate the various color systems. The evaluation program consisted cf two phases. Phase I was a general overview/review of several systems, while Phase II was an extensive internal comparative evaluation measurement systems. These were Milton-Roy's ColorMate HDS, HunterLab's Ultrascan, Datacolor's CS-5, and BYK-Gardner's The Color Sphere [TCS]. The main comparison criteria were interinstrument agreement [agreement between two instruments ofthe same system], user-friendly software and computer interface capability, vendor amenability to a long-term logistical and maintenance relationship, and price. All systems were evaluated by duplicate measurements on various color tiles, yarns, and polymer flakes-over 1600 measurements on each system. The systems were compared with an instrument matrix, a decision matrix, and a product matrix. The instrument matrix was a comparison qfinstrument parameters, software/math treatments, and economics. The decision matrix was a forced ranking of each system by each criteria category [1–4 scale, with 1 representing the best and 4 representing the worst]. The product matrix accentuated the relative importance ofone criterion category over another by multiplying the forced ranking by the criticality of the category. The criticality of a given category wus determined by consensus within the QIT. Thr combination qf the three matrices allowed the evaluator[.s] t o select the color rneasuremmt system that best satixfied the color measurement needs and requirements of their facility and their products. For this evaluation, all ofthe evaluated systems were superior to the then-current agingsystems. As a result of this methodology, one instrument emerged as clearly superior. © 1994 John Wrley & Sons, Inc. 相似文献
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118.
赵志强 《数字社区&智能家居》2007,(19)
简要介绍了IP骨干网络中对QoS技术的定义和其影响因素,并对目前几种比较流行的QoS模型进行了对比.最后重点介绍了DiffServ模型的工作机制,组成部件和相应的实现算法.通过对一些算法的描述,有助于为对从事网质量传输研究或者传输模型实现的相关人员提供一些感性的认识. 相似文献
119.
“To understand and protect our home planet, to explore the universe and search for life, and to inspire the next generation of explorers” is NASA's mission. The Systems Management Office at Johnson Space Center (JSC) is searching for methods to effectively manage the Center's resources to meet NASA's mission. D-Side is a group multi-criteria decision support system (GMDSS) developed to support facility decisions at JSC. D-Side uses a series of sequential and structured processes to plot facilities in a three-dimensional (3-D) graph on the basis of each facility's alignment with NASA's mission and goals, the extent to which other facilities are dependent on the facility, and the dollar value of capital investments that have been postponed at the facility relative to the facility's replacement value. A similarity factor rank orders facilities based on their Euclidean distance from Ideal and Nadir points. These similarity factors are then used to allocate capital improvement resources across facilities. We also present a parallel model that can be used to support decisions concerning allocation of human resources investments across workforce units. Finally, we present results from a pilot study where 12 experienced facility managers from NASA used D-Side and the organization's current approach to rank order and allocate funds for capital improvement across 20 facilities. Users evaluated D-Side favorably in terms of ease of use, the quality of the decision-making process, decision quality, and overall value-added. Their evaluations of D-Side were significantly more favorable than their evaluations of the current approach. 相似文献