Dynamic stability of modified strain gradient theory sinusoidal viscoelastic piezoelectric polymeric functionally graded single-walled carbon nanotubes reinforced nanocomposite plate considering surface stress and agglomeration effects under hydro-thermo-electro-magneto-mechanical loadings

In this article, dynamic stability analysis of the viscoelastic piezoelectric polymeric nanocomposite plate reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNTs) based on modified strain gradient theory (MSGT) is explored. The viscoelastic piezoelectric polymeric nanocomposite plate reinforced is subjected to hydrothermal and electro-magneto-mechanical loadings. The viscoelastic piezoelectric polymeric nanocomposite plate is rested on viscoelastic foundation. Uniform distribution (UD), various functionally graded (FG) distribution types such as FG-V, FG-X, and FG-O are considered for single-walled carbon nanotubes (SWCNTs). The extended mixture approach is applied to estimation of the elastic properties. The equations of motion are derived by Hamilton's principle. The resonance frequency or the parametric resonance is obtained then dynamic stability region is specified. There is a good agreement between the present work and the literature result. Various parametric investigations are performed for the influences of the small scale parameters, direct and alternating applied voltage, magnetic field, viscoelastic foundation coefficients, and aspect ratios on the dynamic stability region of the viscoelastic piezoelectric polymeric nanocomposite plate. The results indicated that SWCNT agglomeration and surface stress have significant effects on the dynamic stability region and the parametric resonance. Dynamic stability region increases with increasing of thickness to width ratio, magnetic field, applied voltage, static load factor, viscoelastic foundation parameters, and surface density constant, and decreasing of length to width ratio and residual surface stress constant. Also, the dynamic stability region shifts to lower parameter resonance with increasing of temperature and moisture changes. The results can be employed for design of micro-electro-mechanical systems and nano-electro-mechanical systems.     

改性蛭石吸附电镀废水中铜离子的研究

将天然蛭石进行处理制备出改性蛭石.在静态条件下,对改性蛭石处理含铜废水进行了研究,探讨了改性蛭石用量、废水酸度、接触时间、温度对除铜效果的影响.结果表明,在废水pH值5.0～7.0、Cu2 浓度0～100 mg/L范围内,按Cu2 与改性蛭石质量比为1/30投加改性蛭石进行处理,Cu2 去除率可达98%以上,且处理后废水pH值为7.62,废水近中性.含Cu2 为28.6 mg/L的电镀废水经改性蛭石处理后,废水中Cu2 含量为0.36 mg/L,Cu2 含量显著低于国家排放标准.     

Crack detection of structures using modified extreme learning machine (MELM)

In this paper, crack detection and estimation method is presented in structures using modified extreme learning machine. For this purpose, extreme learning machine was modified using modified weights and biases. By using the first three frequencies and mode shapes as input, crack was detected as output. Performance of the proposed method was evaluated by using some numerical examples consisting of a simply supported beam, cantilever beam and fixed-simply supported beam. In addition, noise effect (3% noise level) on the measured frequencies and mode shapes have been investigated. In another work, a portal frame has been studied. The results indicated that the proposed method is effective and fast in crack detection and estimation of structures.     

烟气净化用滤料表面改性及其性能

为改善过滤材料的使用性能,满足焦化厂除尘工况的使用要求,选用聚四氟乙烯乳液对玄武岩针刺滤料(X)、氟美斯针刺滤料(F)、玄武岩与氟美斯复合针刺滤料(XF)进行表面改性,并根据相关标准对滤料改性前后的热学性能、耐氧化性能、抗静电性能进行了测试。结果表明:3种滤料表面改性前后均为放热反应,表面改性前后热分解外推起始温度均在350℃左右,焦炉烟气平均温度在230℃,均高于使用温度,符合使用要求;经氧化剂处理,3种滤料表面改性后断裂强力损失率均值较小,说明抗氧化性能改善;表面改性前X滤料的感应静电等级为A级、F滤料的感应静电等级为A级、XF滤料的感应静电等级为C级,表面改性后X滤料、F滤料、XF滤料的感应静电等级均为B级。     

碾压混凝土坝变态混凝土自动化搅拌加浆设备的研发及应用

现有碾压混凝土坝变态混凝土采用人工挖沟槽、框量加浆的施工方式,其作业效率低、浆液浪费多且加浆均匀性差,始终是变态混凝土施工控制的薄弱环节.介绍了一种搅拌式可调控数字流量加浆的变态混凝土注浆新工艺;运用EDEM离散元软件仿真分析了变态区拌合料中搅拌加浆方式的拌合均匀性,并进行了搅拌工艺参数优化;研发出了一套变态混凝土搅拌...     

一种改进MVI-CFAR检测器的性能分析

VI-CFAR检测器在均匀环境和非均匀环境下均具有较强的自适应性,但若前后两个参考滑窗均存在干扰目标时,VI-CFAR检测性能急剧下降。为克服该问题,本文采用有序统计平均CFAR和有序统计选小CFAR来替代VI-CFAR中最小选择CFAR。所提出的算法不但解决了干扰目标位置随机分布的问题,还解决了当其中一个滑窗的干扰目标数超过最大容限时检测性能下降的问题。在参考滑窗中干扰目标个数与扰噪比均不相同的情况下,分析了统计量VI的变化,有助于评估和设计VI-CFAR类检测器在多目标环境下抗干扰目标的最大容限。仿真结果表明,该改进算法提高了VI-CFAR在多目标环境下的鲁棒性,与其他改进算法相比,其排序处理时间降低一倍。     

纳米银/ds-DNA/聚（3,4-乙烯基二氧噻吩）复合膜修饰电极的制备及应用于过氧化氢无酶传感器

在室温水相中,通过电化学方法在玻碳电极上先聚合了聚（3, 4-乙烯基二氧）噻吩（PEDOT）,然后又电沉积了双链DNA（ds-DNA）和银纳米粒子（Nano-Ag）,制备了Nano-Ag/ds-DNA/PEDOT复合膜修饰玻碳电极（GCE）。对该复合膜进行了表征,并研究了该复合膜修饰电极的电化学行为以及对过氧化氢（H2O2）的电催化还原。结果显示,施加工作电位为-0.3 V时,修饰电极对H2O2有着很好的电催化还原能力,达到稳态电流的响应时间小于5 s。因此,该修饰电极可作为无酶传感器用于对H2O2的快速检测。传感器的催化还原电流与H2O2浓度在10 μM-16 mM范围内呈现良好的线性关系,检出限为2.36 μM（S/N=3）。     

多位取代喹诺酮药物的人工神经网络构效关系研究

利用人工神经网络研究69个喹诺酮类药物的构效关系,分别使用BP(Back Propagate)、LM(Levenberg-Marquardt)和RBF(径向基,Radial Basis Function)三种网络方法研究量子化学方法(MNDO法和AM1法)计算所得到的参数。BP网络结果不收敛,RBF网络收敛速度最快,不超过100次迭代就可得到较精确的迭代结果。LM和RBF两种网络预测训练集的正确率均达到100%。其中使用RBF网络和AM1法所得到的参数预测23个预测集的正确率82.6%,MNDO法预测预测集的正确率78.3%,体现了喹诺酮药物的氢键作用成分,结合多元回归分析和相关的耐药机理研究,提出喹诺酮药物的双氢键作用机理。人工神经网络方法可作为研究药物构效关系和研发新药物的有力工具。     

自适应Kalman滤波器在水下被动目标跟踪中的应用

在水下被动目标跟踪系统中，直角坐标系下的扩展卡尔曼滤波器容易发散而导致滤波精度很差，提出了一种修正极坐标系下的自适应卡尔曼滤波算法，对虚拟噪声进行估计，动态补偿模型线性化误差，消减系统的观测误差．对其滤波理论及算法进行了研究和仿真。仿真结果表明，该算法提高了滤波的稳定性、快速性和精确性，优于一般的扩展卡尔曼滤波算法。     

基于MPSO-CWLS-SVM的瓦斯涌出量预测

针对瓦斯涌出量受多因素影响,传统的预测方法难以建立准确的数学模型,导致预测精度低这一问题。提出一种经改进的粒子群算法(MPSO)优化的基于柯西分布加权的最小二乘支持向量机(CWLS-SVM)算法来预测非线性动态瓦斯涌出量。柯西分布加权的最小二乘支持向量机根据预测误差的统计特性,确定加权规则参数,以达到赋予训练样本不同权值的目的。并用MPSO算法对CWLS-SVM模型的正则化参数λ和高斯核参数σ寻优。利用无线传感器网络采集到的各项历史数据进行实例分析。结果表明,该算法有效的提高了瓦斯涌出量的预测精度,降低了预测误差,为煤矿瓦斯防治提供理论支持。