Rapid synthesis of La0.7Sr0.3MnO3+λ catalysts by microwave irradiation process

Microwave irradiation processing (MIP) was considered as a potential method to synthesize perovskite-type oxides rapidly, cleanly and energy-efficiently. In this paper, La_0.7Sr_0.3MnO_3+λ, a kind of promising catalyst for automobile exhaust purification, was successfully prepared by MIP in not more than 5 min. The sol–gel method was also used for comparison. All the samples were evaluated by catalytic activity tests in the simulated exhaust and characterized by XRD, BET, TEM and XRF analyses. The results showed that the integrated perovskite-type phase and uniform particle size were obtained in the microwave-treated samples. And those ones exhibited a better oxidation activity under slightly oxygen-rich condition than that by sol–gel method, which may be related to more A-site cation vacancies and larger bulk oxygen content generated in MIP. Possible formation mechanism of perovskites in MIP was also discussed.     

Comparison of prototype and rote instruction of English names for Chinese visual characters

This study compared prototype and rote instruction of English names for Chinese visual characters. In the prototype condition, participants were taught the meaning of the prototype that served as the distinctive feature of multicomponent characters. In the rote condition, participants traced the character and wrote its translation. Participants learned more rapidly and maintained more words in the prototype condition.     

坐便器与水箱配件在标准中的配套性要求

详细介绍了坐便器与水箱配件在新标准中的配套性技术要求,分析了2种产品配套性指标和相关的检测方法。     

宽带钢冷轧机颤振控制的数值模拟

本文以较为准确的轧机振动状态下的轧制压力模型为基础，对宽带钢冷轧机干摩擦阻尼减振进行了数值模拟的研究。研究结果与实际观测值相等。     

特种钢用结晶器铜管破裂原因分析

通过对某特钢厂破裂的结晶器铜管进行金相实验、扫描电镜和能谱分析,并结合结晶器的生产、使用及失效过程情况,综合受力分析,认为铜管破裂原因主要是环境介质硫渗入形成硫化物,在拉应力作用下,裂纹沿脆性质点扩展导致的破坏。     

计算机网络安全问题及防范对策

文章简单阐述了当前计算机网络所面临的主要安全威胁,并在此基础上提出了分层控制的方案,建立了不同层次间网络安全的防范措施,希望以此来提高网络安全性。     

Output chattering attenuation between two tracking controllers

In this paper, an output chattering attenuation scheme is proposed for two tracking controllers. The controllers have integral actions and are used to eliminate the steady-state tracking errors. By designing a compensator and reducing the discontinuous switching, the output chattering at the switching points can be attenuated significantly. Moreover, combining with the generalized Kalman-Yakubovich-Popov (KYP) lemma and the parameter-dependent Lyapunov function method, this problem can be characterized in terms of linear matrix inequality (LMI) formulation. Finally, the simulation results demonstrate the effectiveness of the proposed method.     

未知环境下机器人障碍物检测技术

未知环境下地面的不平坦性和机器人相对障碍物位姿的不确定性会造成障碍物特征提取困难,为了准确检测障碍物特征,采用3维相机获取机器人周围环境的灰度图像和距离信息。在此基础上,提出基于灰度信息和3维信息的"阈值法"进行障碍物区域的提取,并针对3维信息"阈值法"剔除的地面与障碍物过渡区域过多,以及机器人相对斜坡方位的不确定性引起的障碍物特征检测不准确,提出区域的恢复算法和表面法线坡度计算。实验结果表明,所提出的算法具有简单、有效、准确和鲁棒性强的优点。