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In this paper, linear stability and chaotic motion of a time-delayednonlinear vehicle system are studied. The stability is determined bycomputing the spectrum associated with a system of linear retardedfunctional differential equations, which reveals that a loss ofstability occurs following a Hopf bifurcation. Beyond the critical valuefor linear stability, the system exhibits limit cycle motions.Subharmonic, quasi-periodic and chaotic motions are observed for asystem excited by a periodic disturbance. 相似文献
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Zhaoheng Li Qijun Yu Xiaowen Chen Hao Liu Jiyao Zhang Junlu Zhang Yongmin Yang Jiangxiong Wei 《Journal of Thermal Analysis and Calorimetry》2017,127(3):1897-1909
The compounds of MgO–silica fume (SF) pastes constitute magnesium silicate hydrate (M–S–H) in a new generation of basic castables. However, Mg(OH)2 is a common reaction product with the formation of M–S–H. This study aims to reduce the formation of Mg(OH)2 in MgO–SF pastes. In this study, MgO powders were prepared by calcining magnesite at different temperatures and then mixed with SF and water to prepare MgO–SF pastes. The properties of MgO powders were characterized, and the pH values in the pore solutions of MgO–SF pastes were measured. The MgO–SF pastes cured for 90 days were calcined at 500, 700, 900 and 1200 °C, and the microstructure was characterized afterward. The results showed that both the reactivity of MgO powders and the pH value of the pore solution of MgO–SF pastes were diverse, which essentially depended on the grain sizes and the crystalline degree of MgO. Increasing the calcination temperature of MgO was beneficial to reduce the formation of Mg(OH)2 or even stop it when using MgO calcined at 1450 °C. Enstatite and forsterite formed for all MgO–SF pastes after calcination. However, the microstructure of MgO–SF paste with MgO calcined at 1450 °C was denser than others. MgO–SF pastes were suitable for the new-generation refractory castables. Notably, using MgO calcined at 1450 °C is more appropriate. 相似文献
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航空发动机工作时燃烧室内发生复杂的物理化学变化,生成大量带电粒子,导致发动机尾气静电带电;理论分析了发动机喷流尾气中带电粒子产生演化过程和带电影响因素,讨论对比了多种测试原理与传感器方案,确立了非接触式静电感应测试方案,研制了共轴喇叭状静电传感器和静电监测系统,开发了自动测试软件并对某型航空发动机进行了机载尾气静电带电试验研究,验证了测试平台的有效性,成功获得了大量喷流尾气静电信号;研究结果表明:航空发动机正常工作时喷流尾气中带电粒子总体显正极性,平均体电荷密度约为0.077 nC/m3,发动机等效充电电流为2.26 nA。 相似文献
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OptoelectronicButterflyInterconnectionImplementationofann-bitParallelFullAdditionandSubtraction¥WANGNaxin;SUNDegui;HELiming;W... 相似文献
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本文提出了-种光学非线性薄膜线性参数的方便有效的测量方法,测量了ZnSe非晶态光学薄膜的线性折射率和消光系数。在此方法中,实验数据的计算与处理由-套计算机软件来完成。最后,文章对测量精度进行了简单的讨论。 相似文献
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Optical butterfly interconnection and four primary optical perallel logic opera-tions are implemented by means of phase grating and liquid crystal light valve (LCLV),whichoffers a simple new scheme for implementing optical butterfly interconnections and digitalcomputations. 相似文献
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Jingnan Wu Zhaoheng Ling Leandro R. Franco Sang Young Jeong Zewdneh Genene Josué Mena Si Chen Cailing Chen Prof. C. Moyses Araujo Prof. Cleber F. N. Marchiori Joost Kimpel Xiaoming Chang Furkan H. Isikgor Qiaonan Chen Hendrik Faber Prof. Yu Han Frédéric Laquai Prof. Maojie Zhang Prof. Han Young Woo Prof. Donghong Yu Prof. Thomas D. Anthopoulos Prof. Ergang Wang 《Angewandte Chemie (International ed. in English)》2023,62(45):e202302888
The determination of molecular conformations of oligomeric acceptors (OAs) and their impact on molecular packing are crucial for understanding the photovoltaic performance of their resulting polymer solar cells (PSCs) but have not been well studied yet. Herein, we synthesized two dimeric acceptor materials, DIBP3F-Se and DIBP3F-S, which bridged two segments of Y6-derivatives by selenophene and thiophene, respectively. Theoretical simulation and experimental 1D and 2D NMR spectroscopic studies prove that both dimers exhibit O-shaped conformations other than S- or U-shaped counter-ones. Notably, this O-shaped conformation is likely governed by a distinctive “conformational lock” mechanism, arising from the intensified intramolecular π–π interactions among their two terminal groups within the dimers. PSCs based on DIBP3F-Se deliver a maximum efficiency of 18.09 %, outperforming DIBP3F-S-based cells (16.11 %) and ranking among the highest efficiencies for OA-based PSCs. This work demonstrates a facile method to obtain OA conformations and highlights the potential of dimeric acceptors for high-performance PSCs. 相似文献
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