基于彩色图像处理的浮选尾煤灰分软测量研究

浮选尾煤灰分是浮选产品的一个重要指标。针对选煤厂浮选尾煤灰分多采用离线检测而无法实现在线准确测量,以及当前浮选软测量多采用单一的灰度图像从而导致软测量模型精度及适应性较差的问题,提出了一种基于彩色图像处理的浮选尾煤软测量方法,建立了基于最小二乘支持向量机(LSSVM)的浮选尾煤灰分软测量模型。模型以不同颜色空间的彩色特征、灰度均值以及浓度特征为输入变量,以尾煤灰分作为输出变量,采用粒子群优化算法对LSSVM模型参数进行优化。结果表明：所建立的尾煤灰分软测量模型可以较好地实现浮选尾矿灰分的在线预测,引入浮选尾矿图像的彩色特征可以提高尾煤图像分析的精度,预测精度达96.89%。研究成果在柳湾选煤厂现场应用,并取得了较好的尾矿灰分测量效果。     

再生混凝土多孔砖的配合比设计

根据再生混凝土的特点,选出4种主要因素,并按正交试验的方法设计再生混凝土多孔砖的混凝土配合比试验。经过试验,排出各因素对指标的影响顺序,从而确定再生混凝土多孔砖的最优配合比。     

Electrolytic groundwater circulation well for trichloroethylene degradation in a simulated aquifer

An in situ groundwater remediation process, termed EGCW, was developed in this study by integrating in-well groundwater electrolysis into groundwater circulation well. Groundwater circulation carries electrolytically generated O_2 and H_2 into the impacted aquifer for in situ biodegradation of contaminants. In a two-dimensional tank filled with field sandy sediments,simulated trichloroethylene(TCE)-contaminated groundwater was circulated between an injection well with electrodes inside and a pumping well. Results from a 50-day EGCW experiment show that in-well electrolysis oxygenated most region near the injection well, and 10 mg/L TCE was mainly biodegraded aerobically to about 2.7 mg/L(73% removal) by the indigenous microbes. Aerobic TCE degradation was enhanced by the pulsed addition of acetate. Together with the proofs of stable carbon isotope fractionation(enrichment factor:-0.57‰–-1.53‰) and microbial community variation after EGCW treatment, aerobic cometabolism was proposed to be the most likely mechanism for TCE degradation. It is interesting to find that the intrinsic organic carbon in aquifer matrix could fuel the aerobic TCE degradation, particularly at low TCE concentrations. EGCW treatment is advantageous in terms of supplying appropriate dosages of electron acceptor(O_2) and donor(H_2) for in situ bioremediation because groundwater electrolysis and circulation are expedient and controllable.     

蓝宝石衬底的斜切角对GaN薄膜特性的影响

利用金属有机物化学气相沉积技术在具有斜切角度的蓝宝石衬底(0～0.3°)上生长了非故意掺杂GaN薄膜,并采用显微镜、X射线双晶衍射、光荧光及霍尔技术对外延薄膜的表面形貌、晶体质量、光学及电学特性进行了分析.结果表明,采用具有斜切角度的衬底,可以有效改善GaN外延薄膜的表面形貌、降低位错密度、提高GaN的晶体质量及其光电特性,并且存在一个衬底最优斜切角度0.2°,此时外延生长出的GaN薄膜的表面形貌和晶体质量最好.     

A novel Electro-Fenton-Like system using PW11O39Fe(III)(H2O) as an electrocatalyst for wastewater treatment

A novel Electro-Fenton-Like (EFL) system was developed using the Keggin-type iron-substituted heteropolytungstate anion PW₁₁O₃₉Fe(III)(H₂O)⁴⁻ to substitute for Fe³⁺ in the conventional Electro-Fenton (EF) system for treatment of water polluted with organic compounds. The EFL system overcomes the drawback of low pH in conventional EF approaches and can be directly applied to neutral water treatment without any pH adjustment. Experimental results for dimethylphthalate (DMP) revealed complete degradation in <80 min in pH 6.86 solution containing 0.1 mM DMP at a potential of −0.5 V and O₂ flow rate of 60 mL min⁻¹. Total organic carbon removal of ∼56% was achieved at 120 min. Comparison with conventional EF oxidation revealed better efficiency of the present system for DMP degradation, suggesting its potential in treatment of water and wastewater with a relaxed pH requirement. The cumulative H₂O₂ concentration generated in situ at the electrode was monitored and the observed degradation rate constants k_obs were determined for different initial DMP concentrations. The ligand exchange reaction of PW₁₁O₃₉Fe(III)(H₂O)⁴⁻ with H₂O₂ and the electron transfer resulting in hydroxyl radicals were examined using HPLC and electrochemical impedance spectroscopy. An electrocatalytic model involving inner-sphere electron transfer and a reaction mechanism for PW₁₁O₃₉Fe(III)(H₂O)⁴⁻ electrocatalytic reduction of H₂O₂ are proposed.     

空化热效应对上游泵送机械密封润滑性能的影响

机械密封端面空化现象是影响机械密封润滑性能的重要因素。采用计算流体动力学方法,基于Antoine公式,建立了考虑空化热效应的计算流体动力学模型,并与常用的仅考虑端面液膜粘温效应的模型进行对比,分析了空化热效应对密封性能的影响。结果表明：在低转速下,空化热效应的影响可以忽略,但在高转速下空化热效应使上游泵送机械密封的高压区形成能力减弱,泵送量降低,开启力降低;在高转速工作条件下分析密封失效机理时,除了考虑黏温效应之外,还要考虑空化热效应的影响;空化热效应使螺旋槽槽区局部温度比仅考虑黏温特性时稍高;考虑空化热效应时,动环端面空化发生程度最严重,由动环端面沿膜厚方向至静环槽底,空化区域越来越小,槽底空化区域最小,此规律与仅考虑黏温关系时相反。     

Thin-film composite forward osmosis membranes with substrate layer composed of polysulfone blended with PEG or polysulfone grafted PEG methyl ether methacrylate

To advance commercial application of forward osmosis (FO), we investigated the effects of two additives on the performance of polysulfone (PSf) based FO membranes: one is poly(ethylene glycol) (PEG), and another is PSf grafted with PEG methyl ether methacrylate (PSf-g-PEGMA). PSf blended with PEG or PSf-g-PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaCl (1 mol?L⁻¹) and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSf with 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L?m⁻²?h⁻¹ than the commercial HTI membranes (6–8 L?m⁻²?h⁻¹) under the FO mode. Our study suggests that hydrophobic interface is very important for the formation of polyamide, and a small amount of PSf-g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.     

投资项目的不确定性与风险分析

阐述了投资项目的不确定性和风险的区别和联系以及风险分析的必要性、作用、内容和步骤。     

PtCu alloy nanotube arrays supported on carbon fiber cloth as flexible anodes for direct methanol fuel cell

The rapid development of flexible and portable electrochemical energy devices has promoted the demand for flexible and lightweight electrocatalysts. Here we report flexible high performance electrocatalysts based on PtCu alloy nanotube arrays on carbon fiber cloth (CFC) (PtCu ANTAs/CFC) for direct methanol fuel cell (DMFC). Compared with Pt NTAs/CFC and commercial Pt/C, the PtCu ANTAs/CFC electrocatalysts exhibit significantly improved electrocatalytic activity and durability. Furthermore, the PtCu ANTAs/CFC electrocatalysts show excellent flexibility and they can keep almost constant electrocatalytic performance under the different distorted states, such as normal, bending and twisting states. The improved performance of the flexible PtCu ANTAs/CFC electrocatalysts can be ascribed to unique ANTAs, synergistic effect between Pt and Cu, and porous structure of CFC. This work shows the significant progress of high‐performance Pt‐based flexible anodes for DMFCs. © 2016 American Institute of Chemical Engineers AIChE J, 62: 975–983, 2016     

Residual stress distribution modification caused by weathering in polypropylene and polystyrene

A study has been made of changes in residual stress distributions caused by weathering in polypropylene and polystyrene. Chemi-crystallization has a major effect in polypropylene and an analysis based on the volumetric changes that occur on crystallization has been developed. Close to the surface, fractional crystallinity changes up to 4% are caused by photodegradation (X-ray measurements by Rabello and White (18)). It is estimated that this would cause a tensile residual stress of ～2MNm^?2 to form at the surface if there were no preexisting residual stresses; in the case examined here, the effect of this shrinkage stress was to reduce the compressive residual stress to a small value (<1MNm^?2). Additional changes caused by stress relaxation prior to completion of chemi-crystallization resulted in net tensile stresses near to the surface of the photo-degraded polypropylene. The changes occur almost symmetrically in polypropylene even if the molding is exposed on one surface only. A similar analysis has been made for thermoplastics in which the changes occur only at the exposed surface, comparing the results with measurements made on a glass fiber reinforced grade of polypropylene. In this case the analysis predicts that the stress changes by 2–3MNm^?2 near the surface, enough to develop tensile stresses up to 2MNm^?2 there if the compressive residual stress at the beginning is fairly small, in fairly good agreement with observed changes. Glass fiber reinforced polypropylene does not relax as readily as unfilled polypropylene and better agreement is to be expected without any allowance for stress relaxation. The analysis for one-sided chemi-crystallization allows calculation of the resulting distortion in terms of the curvature: this was estimated at 0.33m^?1, compared to the measured value of 0.44 m^?1. Volumetric changes also occur in noncrystalline polymers and a similar analysis based on data obtained with polystyrene (17) confirms that these changes can explain the observed development of tensile residual stresses on weathering. In the example studied here surface stress changes of 2–3MNm^?2 are predicted and this accounts for a large proportion of the change in residual stress obtained by direct measurement.