Effect of H_2 dilution on the structure and properties of nc-CrC/a-C:H coatings deposited by a hybrid beams system

Nanocomposite Cr C/hydrogenated amorphous carbon(nc-CrC/a-C:H) coatings were deposited by a hybrid beams system comprised of a hollow cathode ion source and a cathodic arc ion-plating unit with varying H_2 flow rates. The influences of H_2 flow rates on the morphologies, microstructures, and properties of the coatings were systematically studied. The morphologies and microstructures of the coatings were characterized by SEM, AFM, XPS, Raman spectroscopy, GIXRD, and HRTEM. The mechanical and tribological properties were measured by a nano-indenter, scratch tester, and ball-ondisk tribometer. The wear tracks were evaluated using 3D profilometer, optical microscope, and EDS analysis. It has been found that a moderate H_2 flow rate can effectively smooth the surface, enlarge the fraction of a sp~3 bond, and improve the properties. The coating exhibits the highest hardness and elastic modulus at the H_2 flow rate of 40 sccm. A superior combination of adhesion strength,friction coefficient, and wear resistance can be achieved at the H_2 flow rate of 80 sccm.     

Liutex-based vortex control with implications for cavitation suppression

Viewed as sinews and muscles of fluid motion,coherent vortical structures with their interactions are key to understanding the flow dynamics.Based upon this observation,we explore the possibility of efficient flow control by directly manipulating vortices numerically inside the flow field based on the vortex definition and identification system of Liutex.The objective is twofold:(1)to study the vortex dynamics,for example,by observing the response of the flow to strengthening or weakening of certain vortices,and(2)to obtain efficient vortex-based control strategies which might lead us to practical applications.In the present numerical study,the manipulating of vortices is achieved by introducing additional source(force)terms to the Navier-Stokes equations,which hereafter will be collectively called Liutex force field model.Methodologies including controlling the rotation strength and centripetal force of particular vortices are detailed in a flow past a cylinder with different control purposes at Reynolds number of 200.Further examples are provided with a cavitating flow around two-dimensional Clark-Y hydrofoil,with particular interests on cavitation suppression.It is illustrated particular vortex with cavitation encircled could be effectively suppressed.     

LiCl-KCl-LaCl_(3)熔盐体系中La^(3+)的反应动力学机理北大核心CSCD

在LiCl-KCl共晶盐中,研究了在不同温度下La^(3+)的反应动力学机理。首先,在723~873 K范围内,利用循环伏安法(CV)测得La^(3+)的扩散系数D为3.06×10^(-5)~6.08×10^(-5)cm^(2)/s,并根据Arrhenius方程计算了La^(3+)在电解质中的扩散活化能E_(D)=34.51 kJ/mol。随后,利用电化学阻抗谱技术(EIS)研究了La^(3+)在电极上的动力学参数并测得交换电流密度i_(0)为0.48~1.39 A/cm^(2)、反应速率常数k_(0)=2.04×10^(-4)~5.90×10^(-4)cm/s及反应活化能E_(a)=35.04 kJ/mol。通过Nyquist图和拟合的等效电路图研究La^(3+)在W电极上的反应动力学机理,发现在LiCl-KCl共晶盐中La^(3+)的电化学反应速率不仅受扩散控制还受电荷转移控制,且与温度成正相关。     

基于Solidworks的锚杆锚索应力传感器弹性体设计仿真分析

为使设计、分析、优化设计过程实现无缝衔接,进一步提高设计速度及有效性,通过三维仿真软件Solidworks,并利用自身模块Simulation Xpress对应力传感器元件部分的弹性体进行设计及静力学仿真分析,以此作为参考,对弹性体贴片位置的设计及弹性体有效性设计进行初步验证其可行性。通过对Solidworks仿真分析方面的各种插件进行简单介绍,使得利用Solidworks进行设计的过程中可合理选择对应的插件无缝地进行仿真,以实现优化设计,进一步提高设计的有效性及速度。     

自适应模糊算法在光伏系统MPPT中的应用

针对光伏电池的非线性特性,介绍了最大功率点跟踪的原理,并详细分析了常规控制算法在光伏系统最大功率跟踪控制中的优缺点,提出将自适应模糊控制算法应用到光伏系统最大功率点跟踪的控制中,自适应模糊控制能快速响应外界环境的变化,在最大功率点无明显振荡现象.实验结果表明,该方法能使系统稳定工作在最大功率点,同时能对外界环境的变化做出快速反应.     

江西省城市室内环境电磁辐射水平研究

本文报道了江西省城市室内环境中电磁辐射水平调查结果,并对市场上部分灯具的电磁辐射进行了调查,研究了灯具对室内环境电磁辐射水平的影响.结果表明:1)江西省城市室内环境中电磁辐射仍处于较低水平,在所调查的十个城市共483个调查点位中,电磁辐射范围为0.01～3.53 V/m,平均值为0.23 V/m;2)通讯基站周围室内环境中电磁辐射明显高于其他环境;3)部分灯具的电磁辐射非常高,最高达500 V/m,并使灯具1 m范围内的室内环境电磁辐射水平明显升高,应制定灯具出厂环保标准并加强灯具市场的管理.     

合成塔出口气锅炉给水换热器上封头泄漏的处理及光刀机设计

合成塔出口气锅炉给水换热器防爆隔膜板裂,上封头泄漏引起着火,对事故的应急处理,中修消缺处理方法及现场光刀机设计作了介绍。     

涂料行业的环保政策解读及应对策略

通过对防治大气污染的环保法规与政策进行横向和纵向的对比,讨论了特殊危险原料与对涂料产品的环境标志认证,分析了从源头控制涂料工业对环境的污染的可能性,提出了不同种类的涂料进行清洁生产的方式,最终讨论了为使涂料生产达到环保标准要求的应对策略。