This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of
static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal
are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of
journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic
bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the
dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered
in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled
electromechanical dynamics analysis of rotor system equipped with magnetic bearings. 相似文献
Approved by the Ministry of Culture, a delegation consisting of 16 curators of national museumsvisited China for exchanges from 20 to 29 September 2013. The curators came from 14 central and eastern European countries （hereinafter referred to as＂CEEC＂） including Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Macedonia, Montenegro, Poland, Romania, Serbia, and Slovenia. 相似文献
Recent reforms in science education have supported the inclusion of engineering and their practices in K-12 curricula. To this end, many classrooms have incorporated engineering units that include design challenges. Design is an integral part of engineering and can help students think in creative and interdisciplinary ways. In this study, we examined students’ conceptions of design during and after participation in a design-based science curriculum unit. Our study was guided by the following research question: What are students’ views of design after participation in an engineering design-based science curriculum unit and how are these views reflected in their enactment throughout the unit? Using a qualitative approach, we examined students’ conversations throughout the enactment of the curriculum and interviews conducted after the completion of the unit. We found that students had complex and diverse views of design, and these views were reflected in their group discussions throughout the curriculum and design challenge. Students most frequently expressed design as learning and as a process of integration into a coherent whole. These aspects of design were also frequently observed in students’ conversations during the unit. Interestingly, we found evidence of students demonstrating several aspects of design throughout the curriculum that were not explicitly expressed during the student interviews. Taken together, these findings support the complex nature of design as seen at the middle school level.
