铁阳极在浓NaOH溶液中的极化特征

使用极化曲线、电解曲线对纯铁电极在浓NaOH 溶液中的极化过程进行了研究. 结果表明, 碱溶液温度越高, 碱浓度越低,电流密度越高, 铁阳极越容易发生钝化;但在某些情况下, 铁电极出现钝化的现象很微弱甚至观察不到.电解法制备高铁酸盐的适宜条件为, 温度25-35 ℃, 极化电流密度≤4.7 mA·cm-2, 碱浓度≥ 14.5 mol·L-1. 用电化学阻抗谱(EIS)研究了上述极化过程中电极表面的阻抗变化情况, 据此描述了铁阳极在浓NaOH溶液中超钝化区极化时的阶段特征.     

石墨炉原子吸收光谱法绝对分析

石墨炉原子吸收光谱法(GFAAS)绝对分析近年来得到了较显著的发展,其主要原因是由于GFAAS中基体干扰问题获得了解决;用以描述GFAAS性能的特征质量MOE值相对稳定;以及用L’vov提出的计算MOT值的式子算出的32个元素的MOT值已比较接近其实验MOE值。大量数据表明完全有可能实现GFAAS绝对分析。     

Numerical study of a well boat operating at a fish farm in current

Dynamic response of a well boat operating at a fish farm in current is investigated numerically. An objective is to determine the operational conditions of the well boat. In terms of the fish farm, a realistic set-up (with single cage) is considered, including a floating collar, an elastic sinker tube, a flexible-closed net cage and a complex mooring system. A time-domain solution is used to find the steady configuration and response. Transverse viscous current loads are estimated using the cross-flow principle. The drag coefficients are obtained empirically by considering cross-sectional details, free surface and three-dimensional (3D) flow effects. The drag force is experimentally validated. The effect of the ship wake on the net loading is also assessed.The most critical scenario with the well boat placed at the weather side of the fish farm is analyzed in detail. Critical response variables for operational limits are the maximum anchor-line tensions and floater stresses. Numerical results show that the anchor loads will increase more than 40% in small current velocities and up to 90% in high current velocities due to the viscous current loads on the boat. There is also a strong increase of the floating collar deformations and stresses when the well boat is in contact with the floating collar.A sensitivity analysis has been carried out to identify the physical parameters affecting the anchor loads and the maximum stress in the floating collar. From our studies, the anchor loads are more sensitive to current direction, bottom weight system, sinker tube depth and mooring line properties (pretension load, anchor chain weight, etc.) and less sensitive to other parameters such as floating collar stiffness and cross-sectional drag coefficients of the well boat. The shading effect of the well boat on the fish-farm inflow has been examined and appeared not negligible with 4% to 10% reduction of the anchor loads for the studied current conditions. The maximum stress in the floating collar is sensitive to well-boat loads related parameters (current direction, cross-sectional drag coefficient) and pretension load in the anchor line; not so sensitive to net loading related parameters such as sinker tube depth and sinker tube weight.Lastly, the operational conditions of the well boat at the fish farm were discussed. Numerical results show that the maximum stresses in the floating collar should be of major concern. The loads in the mooring lines are moderate compared with the corresponding breaking limits.     

Comment on “Kirchhoff index in line,subdivision and total graphs of a regular graph”

Let G$G$ be a connected regular graph. Denoted by t(G)$t\left(G\right)$ and Kf(G)$Kf\left(G\right)$ the total graph and Kirchhoff index of G$G$, respectively. This paper is to point out that Theorem 3.7 and Corollary 3.8 from “Kirchhoff index in line, subdivision and total graphs of a regular graph” [X. Gao, Y.F. Luo, W.W. Liu, Kirchhoff index in line, subdivision and total graphs of a regular graph, Discrete Appl. Math. 160(2012) 560–565] are incorrect, since the conclusion of a lemma is essentially wrong. Moreover, we first show the Laplacian characteristic polynomial of t(G)$t\left(G\right)$, where G$G$ is a regular graph. Consequently, by using Kf(G)$Kf\left(G\right)$, we give an expression on Kf(t(G))$Kf\left(t\left(G\right)\right)$ and a lower bound on Kf(t(G))$Kf\left(t\left(G\right)\right)$ of a regular graph G$G$, which correct Theorem 3.7 and Corollary 3.8 in Gao et al. (2012)  [2].     

基于模糊控制的中压异步电机软启动控制器的研究设计

本文介绍了一种基于模糊控制的中压异步电动机软起动器的原理和软硬件设计。根据对电动机起动特性的分析,提出了基于模糊控制的中压电动机软起动的设计方法。通过检测输入电流,在电动机起动过程中,在恒流平滑升压下有效的消除了启动过程中的电流振荡问题,以达到最佳的起动效果。     

单级功率因数校正电路及其开关应力分析

文章给出了几种单级功率因数校正电路的拓扑结构，计算和分析了其功率开关管上的电压应力和电流应力。为设计功率因数校正电路选择适宜的电路拓扑结构提供了一种依据。     

中国低空大气波导出现概率和波导特征量的统计分析

本文简要说明了我们对大气波导的统计方法，并对统计结果作了讨论和分析。文中详细讨论了中国低空大气波导在不同地区的出现情况，说明了它们在各地出现概率随季节月份的变化情况及日变化情况，还说明了悬空波导和贴地波导基本分布状况；对于波导顶高、强度、厚度、高度等特征量，主要给出了它们的平均值和波导在不同数值上的分布。结果表明，我国低空大气波导出现的高概率区是南部沿海、东南沿海、东部沿海和西北地区中部；我国的四大高原、天山以北和东北平原是无波导区；我国低空大气波导的顶高一般在地面上２０００ｍ以内，强度在０～２０Ｍ单位之间，厚度一般是１００～５００ｍ，高度是西北地区绝大部分为０米，沿海地区大多数超过３００ｍ。同时文中也讨论了我国低空大气波导的分布和我国各地的具体地理位置、气候条件的相关情况。     

一种产生大线性复杂度的方法

本文利用矩阵序列来获得大线性复杂度序列,且研究了矩阵的分量序列之间的联系及它们的周期和复杂度。     

高功率激光技术中的光束控制和相关问题

对高功率激光进行了研究。以平顶高斯光束为例,推导出了它通过无光阑和有光阑的近轴ABCD光学系统传输的解析表达式。给出了它的特征参数,包括光束传输因子(M2因子)、陡峭度(K参数)和桶中功率(PIB)并作了物理分析。最后,指出高功率激光光束控制应使光束在靶面上的功率/能量集中度、时间和空间波形、瞄准稳定性以及时间持续性等指标满足应用要求。     

InP中皮秒快速现象

利用测量瞬态反射谱的方法，探索了掺硫、铁、锌以及非掺杂的ＩｎＰ中载流子寿命，观察到非掺杂ＩｎＰ中载流子寿命最长约６０ｐｓ，掺锌ＩｎＰ中载流子寿命３８ｐｓ居中，掺硫和掺铁的寿命最短约１ｐｓ掺硫、铁和锌的ＩｎＰ中载流子寿命下降，是由于掺杂引入了复合中心，这一结果已被喇曼光谱所证实。