Fuzzy reliability analysis of nanocomposite ZnO beams using hybrid analytical-intelligent method

A hybrid analytical-intelligent approach is proposed for fuzzy reliability analysis of the composite beams reinforced by zinc oxide (ZnO) nanoparticle. The fuzzy reliability index corresponding to buckling failure mode of nanocomposite beam under thickness-direction external voltage is computed based on three-levels: (1) fuzzy analysis, (2) reliability analysis and (3) analytical buckling analysis. In fuzzy analysis level, an improved gravitational search algorithm has been applied to determine uncertainty interval for membership levels of reliability index. The adaptive formulation with a dynamical self-adjusting process is used for reliability analysis level based on conjugate first-order reliability method (FORM). The self-adjusting term in conjugate sensitivity vector is used to satisfy the sufficient descent condition for controlling instability of FORM formula while the proposed conjugate scalar factor is computed less than the original conjugate FORM, thus it may be provided with the efficient results for the convex problem. The new and previous sensitivity vectors obtained by conjugate and steepest descent vectors dynamically adjusted the proposed conjugate factor. In the buckling analysis level, an exponential theory in conjunction with the method of energy is utilized. Fuzzy random variables including applied voltage, the volume fraction of ZnO, thickness of beam, spring constant and shear constant of the foundation are considered in studied nanocomposite beam. Survey results indicated that the proposed method can provide stable and acceptable fuzzy membership functions for parametric study. Moreover, the ratio of length to thickness and spring constant of foundation are the more sensitive parameters which affect fuzzy reliability index significantly.

     

银/氯化银电极用于监测混凝土中氯离子含量的研究

采用干湿循环渗透法,通过实验室制备的银/氯化银电极来监测混凝土中的氯离子含量,测试了电极的响应性能和长期稳定性,研究了总氯离子含量与自由氯离子含量之间、总氯离子含量与电位之间的关系。结果表明:银/氯化银电极电位能比较好地监测到混凝土中氯离子含量变化的过程,具有良好的长期稳定性能。总氯离子含量随自由氯离子含量的增加而增加,两者之间呈现幂函数的规律。总氯离子含量随电位上升而下降,两者之间呈指数函数的规律。     

基于STM32的无位置传感器无刷直流电机控制系统

针对现有无刷直流电机控制系统的缺点,提出了基于STM32F103处理器的无位置传感器无刷直流电动机控制系统。设计并实现了该控制系统的硬件电路,并通过软件编程实现了对转子位置的快速检测及电机调速。实验结果表明了该系统的设计成本较低,运行平稳,调速性能良好。     

基于粒子群优化的多核处理器系统节能调度算法

针对嵌入式多核系统中的实时性和能耗问题,提出了基于粒子群优化的多核处理器系统节能调度算法.通过对多核处理器系统任务调度和能量消耗的分析,建立了新的编码策略和相应的目标函数,将任务划分、任务调度及电压选择3个过程整合到粒子群算法的一个单迭代寻优循环中,并兼顾系统的实时性,将问题转化为有约束的粒子群优化问题,利用可行性规则的约束处理技术,形成基于约束粒子群优化的整体节能调度算法.实验结果表明:本文算法能以较快的速度收敛于使系统能耗更少的调度解.     

Mechanical properties and compression sensibility of ironstone aggregate concrete

Radiation-shielding concrete was made with ironstone aggregate. The compressive strength is affected by multi factors. The electrical conductive properties and smart performance was discovered and investigated. Experimental results show that concrete conductivity rapidly declines with increasing loading, and the conductivity is much lower than the initial value of conductive aggregate of concrete, which may be related to special characters of ironstone. This kind of concrete has widely potential applications due to its special characters and low cost. Funded by the National Natural Science Foundation of China(No. 40674060)     

基于2D激光扫描的基准检测技术研究

在机器人自动制孔系统中,基准孔检测的准确性会直接影响整个机器人制孔过程的位置精度。为获取基准孔孔位准确信息,采用激光扫描的方式对基准孔进行检测。设计了2D线激光扫描在基准平面内点云的三维转化方法,通过分析基准孔在扫描仪坐标系下点云的分布特点,提出了一种基于坐标差值的基准孔边界提取算法。通过设定相邻点云在线激光扫描仪坐标系下z轴的坐标差值获取边界点,实验验证该算法能有效地去除点云中的噪声点,获取准确的基准孔边缘特征信息,进而得到准确的基准孔孔位信息。     

薄板坯连铸连轧的轧制设备配置及轧制技术

介绍了CSP（紧凑式带材生产）、ISP（在线带材生产）、FTSC（通用薄板坯连铸）等薄板坯连铸连轧的轧制设备（包括加热炉）和轧制技术－自由轧制技术、无头轧制技术和铁素体轧制技术等。     

北京某矮塔斜拉桥塔上鞍座分丝管的检验标准

矮塔斜拉桥为国内外的一种新兴桥型,目前用于塔柱处鞍座分丝管的检验标准还没有。本文结合北京某矮塔斜拉桥的建设,论述了用于该桥分丝管检验标准产生的背景,给出了用于该桥分丝管具体的检验标准,并且对各条标准作了详细的解释。     

北京某矮塔斜拉桥塔上鞍座分丝管的检验标准

矮塔斜拉桥为国内外的一种新兴桥型,目前用于塔柱处鞍座分丝管的检验标准还没有。本文结合北京某矮塔斜拉桥的建设,论述了用于该桥分丝管检验标准产生的背景,给出了用于该桥分丝管具体的检验标准,并且对各条标准作了详细的解释。     

A security enhanced mutual authentication scheme based on nonce and smart cards

There are many mutual authentication schemes proposed in the literature for preventing unauthorized parties from accessing resources in an insecure environment. However, most of them based on smart cards have assumed a tamper resistant condition for the smart card. To solve the problem, Huang, Liu, and Chen (2013) proposed a mutual authentication scheme based on nonce and smart cards and claimed that the adversary was not able to attack and access the system even if he could extract the data stored in the smart card. Unfortunately, in this paper, we will demonstrate that Huang et al.’s scheme is vulnerable to the offline password guessing attack and the privileged insider attack. We also propose an improved scheme to overcome the weaknesses.