Continuous Cloud Point Extraction of Volatile Organic Contaminants from Wastewater in a Multi-Stage Rotating Disc Contactor: Effect of Structure and Concentration of Solutes

Abstract

Cloud point extraction (CPE) has been successfully scaled up to continuously remove aromatic contaminants from wastewater in a multi-stage rotating disc contactor (RDC) using t-octylphenolpolyethoxylate. The extraction performances for the removal of organic solutes with different structures and degrees of hydrophobicity were compared here for both batch and continuous CPE. Included are the volatile aromatics benzene, toluene, and ethylbenzene; volatile chlorinated compounds dichloroethane, trichloroethylene, and tetrachloroethylene; and non-volatile phenolics phenol, o-cresol, and catechol. The higher the K_ow (octanol-water partition coefficient) or hydrophobicity of the solutes, the better the extraction due to the greater affinity of solutes to solubilize into micelles. The empirical linear correlations between log K_ow, log (solute partition ratio), and log (height of transfer unit or HTU) were developed. Toluene is used as a model solute for the study of effect of initial solute concentrations in the continuous RDC. The extraction ability decreases as the concentration of toluene in the wastewater increases mainly due to coacervate entrainment into the overhead effluent.     

A globally convergent trust region multidimensional filter SQP algorithm for nonlinear programming

We propose a trust region multidimensional filter SQP algorithm. The multidimensional filter technique proposed by Gould et al. [SIAM J. Optim., 15 (2005), pp. 17–38] is extended to solve constrained optimization problems. The constraints are partitioned into p parts. The entry of our filter consists of these different parts. Not only the criteria for accepting a trial step would be relaxed, but also the individual behaviour of each part of the constraints is considered. The filter's entries and the acceptance criteria are different from other filter-related algorithms in the literature. It should be noted that the undesirable link between the objective function and the constraint violation function in the filter acceptance criteria disappears. Our algorithm is also combined with the non-monotone technique for accepting a trial step, which leads to a more flexible acceptance criteria. Under mild conditions, global convergence is proved. Numerical results show the robustness and efficiency of our algorithm.     

Part accuracy improvement in two point incremental forming with a partial die using a model predictive control algorithm

As a flexible forming technology, Incremental Sheet Forming (ISF) is a promising alternative to traditional sheet forming processes in small-batch or customised production but suffers from low part accuracy in terms of its application in the industry. The ISF toolpath has direct influences on the geometric accuracy of the formed part since the part is formed by a simple tool following the toolpath. Based on the basic structure of a simple Model Predictive Control (MPC) algorithm designed for Single Point Incremental Forming (SPIF) in our previous work Lu et al. (2015) [1] that only dealt with the toolpath correction in the vertical direction, an enhanced MPC algorithm has been developed specially for Two Point Incremental Forming (TPIF) with a partial die in this work. The enhanced control algorithm is able to correct the toolpath in both the vertical and horizontal directions. In the newly-added horizontal control module, intensive profile points in the evenly distributed radial directions of the horizontal section were used to estimate the horizontal error distribution along the horizontal sectional profile during the forming process. The toolpath correction was performed through properly adjusting the toolpath in two directions based on the optimised toolpath parameters at each step. A case study for forming a non-axisymmetric shape was conducted to experimentally validate the developed toolpath correction strategy. Experiment results indicate that the two-directional toolpath correction approach contributes to part accuracy improvement in TPIF compared with the typical TPIF process that is without toolpath correction.     

Improving the integration of piece wise linear representation and weighted support vector machine for stock trading signal prediction

The integrated piecewise linear representation (PLR) and weighted support vector machine (PLR-WSVM) has shown success in the prediction of stock trading signals. Meanwhile drawbacks of PLR-WSVM exist particularly in a real world setting. For example, the profitability using PLR-WSVM is unstable, it is not reasonable to specify same threshold value for all stocks in PLR, and critical errors in trading signals may significantly reduce the profit. In this paper, we conduct a set of improvements to PLR-WSVM. First, most of absolute technical indicators in input variables are substituted with relative indicators since the relative indicators are generally more helpful in predicting trading signals. Second, a four-class prediction problem is converted into a two-class problem in which one class is a turning point (TP) and the other is an ordinary point. And prior domain knowledge is exploited to identify either buying or selling signals from TPs. Thirdly, a delay-one-day strategy (DODS) is proposed to further correct the predicted trading signals. DODS reduces the critical errors occurring to PLR-WSVM. Finally, a procedure for selecting a threshold in PLR is provided. The threshold is automatically selected by a given percentage of TPs in a training set. The percentage of TPs is easier to understand by investor compared with the threshold. We conduct experimental study over 20 stocks, and the results confirm the expected performance of the improved PLR-WSVM. More importantly, the improved PLR-WSVM provides steady profits in average over the stocks of interest with accepted retracements.     

Enhanced control strategies for a hybrid battery/photovoltaic system using FGS-PID in grid-connected mode

This paper suggests improved control strategies using Fuzzy Gain Scheduling of Proportional-Integral-Derivative (FGS-PID) controller for a hybrid Photovoltaic (PV) and Battery Energy Storage (BES) system under different weather conditions. The proposed scheme is implemented using a two-level control system structure, combining the benefits of the PID as well as the fuzzy logic controller (FLC) for maximum power point tracking (MPPT). Ziegler-Nichols tuning method is also employed to select the initial values of PID gains. Within the period of steady-states and transients, FGS-PID adopts the gains to ensure the stability of the control scheme. It also damps out transient fluctuations and reduces settling time. Also, BES could be employed to provide a stable and reliable power from the output of PV sources to loads. It can enhance the performance of the entire power system during the grid-connected mode. The simulation results under Matlab/Simulink show that the suggested control strategies are robustness, fast transient response and proper steady-state performance in the grid-connected mode in comparison other presented methods.     

对城市道路平面交叉设计的探讨

从交通组织设计的角度出发，广泛参照国内外先进的理论与方法，结合平时工作积累的经验，从交叉口危险点、通行能力、渠化设计的角度进行分析探讨，并提出了一些思路，以供参考。     

一种新型泄油口外置式溢流阀组的研究

为了提高先导压力稳定性,针对溢流阀组原理及问题进行分析,并研究了一种新型的泄油口外置式溢流阀组结构。通过测试结果对比可知,该结构溢流阀组显著提高了系统使用性能及稳定性,并降低了能量损失。     

Enzymatic interesterification of palm and coconut stearin blends

Hard fractions of palm oil and coconut oil, blended in the ratios of 90:10, 85:15, 80:20 and 75:25, were interesterified for 8 h using Lipozyme TL IM. Major fatty acids in the blends were palmitic acid (41.7–48.4%) and oleic acid (26.2–30.8%). Medium‐chain fatty acids accounted for 4.5–13.1% of the blends. After interesterification (IE), slip melting point was found to decrease from 44.8–46.8 °C to 28.5–34.0 °C owing to reduction in solids content at all temperatures. At 37.5 °C, the blends containing 25% coconut stearins had 17.4–19% solids, which reduced to 0.4–1.5% on IE, and the slip melting point (28.6 and 28.8 °C) indicated their suitability as margarine base. The reduction in solid fat index of the interesterified fats is attributed to the decrease in high‐melting triacylglycerols in palm oil (GS₃ and GS₂U type) and increase in triolein (GU₃) content from 1 to 9.2%. Retention of tocopherols and β‐carotene during IE was 76 and 60.1%, respectively, in 75:25 palm stearin and coconut stearin blend.