铁尾矿砂力学特性及再生利用研究进展

铁尾矿砂的储量日趋增加,要减小铁尾矿坝的风险、提高铁尾矿砂的利用率,须明确铁尾矿砂的力学特性.通过对铁尾矿砂静力特性及动力特性的分析发现,尾矿砂的粒径分布是决定尾矿坝稳定及铁尾矿砂再生利用的主要因素之一,细粒含量、干密度、含水率等因素对铁尾矿砂动力特性有一定影响.再生利用铁尾矿砂的主要方式是将铁尾矿砂混凝土、改性铁尾矿砂用作工程材料,水泥、石灰、纤维是改性铁尾矿砂的主要材料.最后指出需进一步研究新型材料取代传统改性材料改善铁尾矿砂的力学特性,从而提高资源利用率.     

A novel bio‐based phthalonitrile resin derived from catechin: synthesis and comparison of curing behavior with petroleum‐based counterpart

The development of bio‐based thermosetting resins with good thermal stability can potentially afford sustainable polymers as replacements for petroleum‐based polymers. We report a practical route to a novel catechin‐based phthalonitrile resin precursor (CA‐Ph), which contains free phenolic hydroxyl groups that result in ‘self‐curing’ at elevated temperatures to afford a thermostable polymer. Comparison of the performance of this CA‐Ph resin with that of a conventional petroleum‐based bisphenol A phthalonitrile resin (BPA‐Ph; containing 5 wt% of the curing agent 4,4′‐diaminodiphenylsulfone) revealed that CA‐Ph exhibits a lower melting point and curing temperature. Cured CA‐Ph resin retains 95% of its weight at 520 °C under a nitrogen atmosphere, which compares favorably with results obtained for BPA‐Ph resin that retains 95% of its weight at a lower temperature of 484 °C. Kinetic results indicated that the curing reactions of both CA‐Ph and BPA‐Ph systems follow an autocatalytic mechanism. These results suggest that catechin is a useful bio‐based feedstock for the preparation of self‐curing and thermally stable phthalonitrile resins for advanced technological applications. © 2017 Society of Chemical Industry     

利用煤矸石制备泡沫陶瓷的研究

以煤矸石为研究对象,利用XRD和XRF技术,研究了煤矸石的矿物组成和化学成分.以煤矸石和低品位铝矾土为主要原料,长石作为助熔剂,振实成型后在1 200℃下焙烧成泡沫陶瓷.结果 表明,当原料中煤矸石的含量为61wt％时,所制备泡沫陶瓷的基本性能为:导热系数0.059 W/(m·K)、体积密度118.6 kg/m3、体积吸水率1.3％、抗压强度1.3 MPa、抗折强度1.4 MPa.利用煤矸石制备泡沫陶瓷,为煤矸石综合利用提供了一条可行的途径.     

净水水处理剂中有害杂质在水中残留物分析与风险评估

与欧盟和美国标准相比,我国硫酸铝和硫酸铵标准缺少对水处理剂中有害杂质镍、锑、硒、银、吡啶、氰化物、六价铬的检测;次氯酸钠缺少对水处理剂中有害杂质汞、铬、镉、铁、镍、锑、硒、银、六价铬的检测。结合某市2019年上半年13个水厂出厂水和原水的检测数据,剔除了5项始终低于检出限的有害杂质指标,以及2项出厂水浓度低于原水浓度的有害杂质指标。建议该市硫酸铝和硫酸铵的检测项目可以在原有国标基础上增加锑、硒;次氯酸钠可以增加汞、锑、硒。     

内插法在相关干涉仪测向体制中的应用

测向误差的减小一直以来都是无线电测向精度提高的一个难点,对于不同的测向体制所采用的减小测向误差的方法都不尽相同。本文主要介绍的是相关干涉仪测向体制的基本原理以及通过内插法的应用来减小测向误差的方法。     

Design and optimization of ceramic membrane structure: From the perspective of flux matching between support and membrane

The support flux was first investigated as a separate influencing factor for its effect on performances of ceramic filtration membranes. Three pre-membranes were prepared by tape-casting and then transfer-coated to supports to form dual-layer ceramic membranes after sintering. Experiments demonstrated that membrane layers with almost the same properties were obtained despite the huge difference in support flux. When the support flux increases from 3.120 to 97.53 m³m^?2h^?1, the flux of these three membrane series have increased by 75%, 186% and 228%, respectively. Experimental rules can provide structural design and evaluation from the perspective of permeability. The limit membrane flux of a certain system was derived according to the resistance distribution law of internal membrane structure and the Darcy's theorem. On this basis, a method for designing support flux was proposed. Furthermore, we present a criterion to quickly and easily evaluate the match between the support and the top layer, which is the ratio of membrane resistance to total resistance. Finally, the filtration resistance of penetration caused by suction of membrane particles into the support was measured for the first time, taking the advantage of the transfer-coating method that inherently free of penetration. Our works are expected to deepen the understanding of the ceramic membrane structure and provided guidance for its rational design and optimization.     

基于子系统的非线性时变系统辨识方法

针对非线性时变系统提出一种基于子系统的辨识方法，用于时变多自由度（multiple degree-of-freedom，简称MDOF）系统中非线性的定位和估计，并且无需关于系统的先验知识。所提出的新方法提供一个连续时间模型，MDOF系统按照自由度被分解为不同的子系统。设计正交化算法和误差减小率（error reduction ratio, 简称ERR），可以确定子系统中质量和自由度之间的线性及非线性连接的所有信息。在辨识过程中，时变参数的时间表达式可以由新方法准确给出。用一个3自由度（degree-of-freedom, 简称DOF）集中质量系统和一个机械臂结构的辨识过程为例，对所提出的方法进行验证。由于简单性及高效性，此方法将在实际工程中取得广泛的应用。     

粘性条件下含不同导叶数的液力透平水力损失分析

为了研究粘性条件下含不同导叶数的液力透平内水力损失的分布情况,采用CFD方法以3种不同黏度工质对3种不同导叶数的泵作液力透平进行数值计算,分析工质黏度对含不同导叶数的液力透平水力损失分布的影响规律。结果表明:叶轮内的水力损失在透平总水力损失中所占比重超过50%,是透平内的主要水力损失;相同流量与工质下,叶轮内的水力损失随着导叶数的增加而减小,叶轮内的流动受导叶数影响显著,蜗壳、导叶等其他过流部分内的流动受导叶数影响较小;随着工质黏度的增加,相同导叶数透平各过流部分的水力损失基本呈增大趋势;在透平叶轮前添加合适叶片数的导叶能够改善叶轮内流动的状况,减小叶轮内水力损失。