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801.
802.
针对滑环失效数据较少的特点,构建导电滑环磨损失效模型,结合小子样数据处理法和随机性理论对滑环摩擦副进行可靠性评估研究。首先,考虑滑环摩擦副在热力电多场耦合环境下的特点,应用传热学、赫兹理论、能量守恒定律量化多场耦合对滑环摩擦副的影响,再结合Archard模型理论构建导电滑环摩擦副磨损失效模型。然后,采用小子样数据的虚拟增广法和Boot-strap法对仿真数据进行扩展,根据滑环磨损特征量分布规律分别得到随机失效阈值与固定阈值下的可靠度函数曲线,以某厂制造的导电滑环为例,进行滑环摩擦副可靠性评估,实验结果表明随机失效阈值下的可靠度与实际更接近。研究表明所构建的磨损模型和方法可以有效地对导电滑环进行可靠性评估,避免了传统的必须依赖大量试验数据的方法,解决了缺少滑环试验数据而难以进行可靠性评估的问题,填补了导电滑环可靠性研究的空白。 相似文献
803.
804.
The paper deals with the problem of lateral bending for the five-layer panel with the lightweight filler that is reduced to the bending problem of a beam fixed at the end sections. To solve the differential equations describing the beam bending, the Euler-Lagrange variational principle is used. 相似文献
805.
In this paper, we introduce a concept of coordinated turn that means the application of the lifting force being perpendicular to the UAV velocity vector and parallel to the surface on which the exact point target is located. Analytical solutions of the corresponding differential equations of the coordinated turn are derived. 相似文献
806.
The effect of detuning the partial frequencies of MEMS gyroscopes on its amplitudefrequency response is investigated. The formulated mathematical model allows defining requirements for the tolerances on gyros parameters, which determine the values of gyros partial frequencies, at the design stage of the sensor. 相似文献
807.
Active influence dimension of film cooling along the blade profile is investigated with using the Spalart–Allmaras turbulence model. The cooling effectiveness of vane platforms and vane fillets is studied with the use of perforation holes on the leading edge. 相似文献
808.
The paper highlights results of analyzing the gating systems in terms of assurance of slag retention at the stage when the mold cavity is filled up with the melt. Quantitative values of parameters as to assessment of slag retention were obtained that can be applied in selecting the gating system type for a casting. 相似文献
809.
We present a design lay-out diagram of the reusable space transportation system that consists of an aerospace transformed vehicle that is injected into an orbit by means of the first and second stages. Some starting configurations of such system with the first and second stages are considered. 相似文献
810.
Rachael L. Beaton Giuseppe Bono Vittorio Francesco Braga Massimo Dall’Ora Giuliana Fiorentino In Sung Jang Clara E. Martínez-Vázquez Noriyuki Matsunaga Matteo Monelli Jillian R. Neeley Maurizio Salaris 《Space Science Reviews》2018,214(8):113
Old-aged stellar distance indicators are present in all Galactic structures (halo, bulge, disk) and in galaxies of all Hubble types and, thus, are immensely powerful tools for understanding our Universe. Here we present a comprehensive review for three primary standard candles from Population II: (i) RR Lyrae type variables (RRL), (ii) type II Cepheid variables (T2C), and (iii) the tip of the red giant branch (TRGB). The discovery and use of these distance indicators is placed in historical context before describing their theoretical foundations and demonstrating their observational applications across multiple wavelengths. The methods used to establish the absolute scale for each standard candle is described with a discussion of the observational systematics. We conclude by looking forward to the suite of new observational facilities anticipated over the next decade; these have both a broader wavelength coverage and larger apertures than current facilities. We anticipate future advancements in our theoretical understanding and observational application of these stellar populations as they apply to the Galactic and extragalactic distance scale. 相似文献