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建立了行星齿轮-转子系统的非线性动力学模型,系统模型将内啮合刚度嵌入齿圈刚度进行建模,考虑了转子扭转效应、齿侧间隙、时变啮合刚度和综合传动误差等因素.采用分岔图、最大李雅普诺夫指数(LLE)、庞加莱截面图和相图来分析响应特征.研究齿轮与转子间扭转振动位移响应,分析了旋翼轴与传动轴扭转刚度比变化影响规律.研究发现,系统具有非线性动力学特性,通过准周期分岔和倍周期分岔进入混沌运动,获得了系统避免失稳的刚度比阈值区间.研究为直升机主减速器行星齿轮-转子系统的动力学设计和扭转振动控制提供了参考. 相似文献
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Ultraviolet‐crosslinked hydrogel sustained‐release hydrophobic antibiotics with long‐term antibacterial activity and limited cytotoxicity
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To prolong erythromycin (EM) release and prevent the side effects of EM, a Pluronic F‐127 diacrylate macromer (PF127) was synthesized and then self‐assembled into micelles with their hydrophobic cores loaded with EM. The EM‐loaded micelles were mixed with a photoinitiator to form the EM/PF127 hydrogels rapidly under a low‐intensity UV light. Afterward, the hydrogel properties, antibacterial performance, and cytotoxicity of this novel hybrid hydrogel were investigated. The results show that the EM/PF127 hydrogel had a rapid gelation time. The sustained release of EM reduced its side effects. With controlled antibacterial activity, the use of EM would be safer and more efficient. What is more, the EM/PF127 hydrogel showed a slight cytotoxicity, and this suggests great potential application as antibacterial hydrogels in the prevention of postoperative infection. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40438. 相似文献
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Partha Majumdar Andrey Chernykh Hanzhen Bao Elizabeth Crowley Mingqiang Zhang James Bahr Michael Weisz Chad Ulven Tingting Zhou Robert B. Moore Bret J. Chisholm 《Polymer Engineering and Science》2014,54(7):1648-1663
An array of perfectly alternating polycarbonate‐polydimethylsiloxane (PC‐PDMS) multiblock copolymers possessing systematic variations in block molecular weights were successfully produced by coupling preformed PC and PDMS telechelic oligomers using hydrosilylation. Based on gel permeation chromatography results, the multiblock copolymers were essentially void of the oligomeric precursors. Despite the relatively large difference in solubility parameter between PC and PDMS, the multiblock copolymers exhibited significant partial miscibility between the two phases. As expected, the degree of partial miscibility was dependent on the molecular weight of the blocks with the extent of partial miscibility increasing with decreasing block molecular weights. Morphological characterization using small angle X‐ray scattering showed that, at a given PC block molecular weight, the uniformity of the two phase morphology increased with increasing PDMS block molecular weight, which is consistent with a decrease in the extent of phase mixing with increasing PDMS block molecular weight. POLYM. ENG. SCI., 54:1648–1663, 2014. © 2013 Society of Plastics Engineers 相似文献
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推理技术是故障诊断系统的核心,目前针对复杂系统的故障推理仍然是个难题,提出了将模糊神经网络与事例推理相融合的集成诊断模型,通过规则推理、事例推理和神经网络推理三个子系统的互相验证,既解决了事例推理不能得到最优解的问题,又解决了模糊神经网络训练样本难以选取的问题,将该推理方法用于某武器系统故障诊断,取得了较好地诊断效果. 相似文献
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以浙江海宁尖山工业高新区区域电网为研究对象,考虑高新产业敏感电力负荷对电能质量和供电可靠性的高要求,分析分布式光伏高渗透、网架弱联络的工业高新区配电网面临的问题,开展基于柔性互联、分布式储能、交直流混合微电网、源网荷储协调控制等关键技术的主动配电网应用实践,以电能质量、供电可靠性、光伏消纳能力等评价指标,研究主动配电网关键技术在工业高新区光伏高渗透区域电网的应用模式,分析主动配电网灵活的网络拓扑、主动的控制策略等优势在区域配电网发挥的作用与意义,展望主动配电网技术在工业高新区配电网的发展前景与方向。 相似文献
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Lei Zhu Mingqiang Wei Jinze Yu Weiming Wang Jing Qin Pheng‐Ann Heng 《Computer Graphics Forum》2013,32(7):371-380
State‐of‐theart normal filters usually denoise each face normal using its entire anisotropic neighborhood. However, enforcing these filters indiscriminately on the anisotropic neighborhood will lead to feature blurring, especially in challenging regions with shallow features. We develop a novel mesh denoising framework which can effectively preserve features with various sizes. Our idea is inspired by the observation that the underlying surface of a noisy mesh is piecewise smooth. In this regard, it is more desirable that we denoise each face normal within its piecewise smooth region (we call such a region as an isotropic subneighborhood) instead of using the anisotropic neighborhood. To achieve this, we first classify mesh faces into several types using a face normal tensor voting and then perform a normal filter to obtain a denoised coarse normal field. Based on the results of normal classification and the denoised coarse normal field, we segment the anisotropic neighborhood of every feature face into a number of isotropic subneighborhoods via local spectral clustering. Thus face normal filtering can be performed again on the isotropic subneighborhoods and produce a more accurate normal field. Extensive tests on various models demonstrate that our method can achieve better performance than state‐of‐theart normal filters, especially in challenging regions with features. 相似文献