Treatment of CNC industry wastewater by electrocoagulation technology: an application through response surface methodology

ABSTRACT

Removal of COD, and several toxic heavy metals (Cu²⁺ and Ni²⁺) from CNC (metalworking fluid) wastewater was investigated using electrocoagulation method (EC) with Fe and Al electrodes. The interaction effects of the current density, reaction time and initial pH were analyzed and were correlated to assess the removal efficiencies for COD, copper, and nickel. Coefficient of determination (R²) and adjusted R² was found to be higher than 96.81% and 92.77; 99.01% and 89.94 for all responses at Fe and Al electrodes, respectively. Removal efficiencies were determined to be 95.72%, 96.03%, 95.22% and 97.11%, 98.51%, 92.49% for COD, copper and nickel at iron and aluminum electrodes, respectively under optimum operating conditions. The operational cost of the EC process for COD, copper, and nickel removal, were found to be 2.54, 3.36, 2.50 €/m³ for iron electrode and 7.16, 8.95, 8.50 €/m³ for aluminum electrode at optimum conditions, respectively. The results provide that The EC process seems to be an effective treatment method for removing COD and several trace heavy metals from the CNC machine (metalworking fluid) wastewater.     

Numerical study of radial temperature distribution in the AlN sublimation growth system

A large radial temperature gradient in the AlN sublimation growth system would lead to non‐uniform growth rate along the radial direction and introduce thermal stress in the as grown crystal. In this paper, we have numerically studied the radial thermal uniformity in the crucible of a AlN sublimation growth system. The temperature difference on the source top surface is insignificant while the radial temperature gradient on the lid surface is too large to be neglected. The simulation results showed that the crucible material with a large thermal conductivity is beneficial to obtain a uniform temperature distribution on the lid surface. Moreover, it was found that the temperature gradient on the lid surface decreases with increased lid thickness and decreased top window size.     

Estimate of the maximum range achievable by non-radiating wireless power transfer or near-field communication systems

Models relating the coupling coefficient of coupled circuits to their physical layout and separation are essentially empirical in nature and have, until very recently, been available exclusively for inductive systems. In this work, we propose elementary models for representing the evolution, with distance, of the coupling coefficient between two dipoles arranged in different configurations. Both the electric and magnetic coupling cases are examined. We demonstrate that in the case of electrically coupled dipoles, with due consideration for specific practical constraints, the coupling coefficient is optimal when the dipoles are asymmetrical and arranged in an axial configuration. We show that the rate of fall of coupling coefficient increases with the relative separation between the dipoles. Finally, a simple formula for estimating the range of all non-radiating resonant power transport devices is proposed.     

Facial expression recognition and its application based on curvelet transform and PSO-SVM

A novel method is proposed for facial expression recognition combined curvelet transform with improved support vector machine (SVM) based on particle swarm optimization (PSO). The whole process is as follows. Firstly, as wavelet transform in two-dimension is good at isolating the discontinuities at edge points and only captures limited directional information, the curvelet transform is applied to extract facial expression feature substitutively. However, the amount of curvelet coefficients obtained in the first stage is too huge to be classified, therefore, all of the coefficients are sorted descendantly and the former larger 5 or 10% are remained while the others abandoned to reduce the dimension. Finally, PSO algorithm is employed to search for the reasonable parameters of SVM to increase classification accuracy. Experimental results demonstrate that our proposed method can form effective and reasonable facial expression feature, and achieve good recognition accuracy and robustness, which is competent for spirit states detection of operators to decrease defect rate of production.     

基于显著性特征的大冰雹识别模型

为了解决目前气象业务中由数字化雷达系统提供的强冰雹指数对强冰雹空报率过高的问题, 依据概念模型对强冰雹回波单体特点的描述, 设计并实现了"悬垂度" 等多个特征提取算法, 为了校验这些特征以及传统的强冰雹指数是否能从各自的角度突显强冰雹单体自身特质, 将较易与其混淆的短时强降水单体作反例进行统计校验, 结果表明它们在两类样本之间的差异是显著的. 以此为基础, 选用基于径向基核函数的非线性支持向量机得到强冰雹识别模型, 并在一种尺度变换的基础上, 将待测样本远离最优分类超平面的相对程度定义为新冰雹指数.实验表明, 本文方法较目前业务上普遍使用的冰雹指数法具有更高的击中率, 同时空报率大大降低. 关键词： 强冰雹识别 风暴单体的悬垂特征 显著性差异特征 支持向量机     

闪电的分形特征研究及其在自动识别中的应用

利用2009年夏季青海地区的快电场变化测量仪的野外观测资料, 对120例地闪和77例云闪辐射场信号的分形特征进行了深入研究, 结果表明地闪辐射场信号的分形维数与云闪辐射场信号的分形维数有明显的差别, 再利用闪电的分形维特征, 构造了5个特征值, 将其作为支持向量机的输入进行地闪和云闪不同放电类型的识别, 有效识别率达到95%以上; 通过构造地闪辐射场时间序列信号的分形维数轨迹图表明分形维数最低点对应于原时间序列的回击位置, 利用分形维数轨迹中的最低点的位置能够快速准确地对地闪辐射场信号的回击点进行检测, 检测率可达到100%. 分形维是闪电的一种具有鉴别性的特征, 可用于闪电的智能分析与自动化处理. 关键词： 闪电信号 分形维数 支持向量机 自动识别     

直觉模糊变换半群的积与覆盖关系

提出了直觉模糊变换半群的(全)直积,圈积,直觉模糊变换半群的覆盖的定义,利用代数的手段讨论了直觉模糊变换半群的积的结合性质,研究了直觉模糊变换半群的积的覆盖关系.     

Minimizing the total completion time on a single machine with the learning effect and multiple availability constraints

This paper considers a single machine scheduling problem with the learning effect and multiple availability constraints that minimizes the total completion time. To solve this problem, a new binary integer programming model is presented, and a branch-and-bound algorithm is also developed for solving the given problem optimally. Since the problem is strongly NP-hard, to find the near-optimal solution for large-sized problems within a reasonable time, two meta-heuristics; namely, genetic algorithm and simulated annealing are developed. Finally, the computational results are provided to compare the result of the binary integer programming, branch-and-bound algorithm, genetic algorithm and simulated annealing. Then, the efficiency of the proposed algorithms is discussed.