Rheological and fractal characteristics of granular sludge in an upflow anaerobic reactor

The rheological and fractal characteristics of the granular sludge in an upflow anaerobic sludge blanket (UASB) reactor were investigated in this study. The influences of sludge concentration and temperature on the rheological properties of the granular sludge were evaluated, and the Bingham model was adopted to describe its rheology. In addition, image analysis was used to determine the sludge fractal dimension. The results indicate that the UASB granular sludge showed a shear-thinning behavior. The relationships between the limiting viscosity and the sludge concentration, as well as the limiting viscosity and temperature could be respectively modeled using an exponential equation and Arrhenius equation well. The Bingham model was able to adequately describe the rheology of the granular sludge. The fractal dimension of the granular sludge, 2.79+/-0.03, was larger than that of some other aggregates, suggesting that the granular sludge were more compact and denser. Furthermore, the relationship between rheological and fractal properties of the granular sludge could be properly described with the model proposed by Shih et al. [1990. Scaling behavior of the elastic properties of colloidal. Phys. Rev. A 42, 4772-4779].     

Investigation on flexural behavior of pretensioned prestressed steel strand high strength concrete large-diameter pipe piles

为研究大直径钢绞线管桩的受弯性能，对3根不同直径钢绞线桩进行足尺试验、理论分析和有限元模拟，对比研究了大直径钢绞线桩的开裂弯矩、裂缝开展及分布、受弯承载力、变形延性和破坏特征等。结果表明：大直径钢绞线桩受弯破坏时受压区高强混凝土压溃，截面中心轴以下钢绞线都达到屈服强度，具有较高的受弯承载力和良好的变形延性；理论分析方法能够较好地预测大直径钢绞线桩的受弯承载力；建立的有限元模型可以合理地模拟大直径钢绞线桩的受弯性能，模型计算结果与试验结果吻合较好。     

框支承玻璃幕墙有限元分析

采用有限元方法进行了框支承玻璃幕墙风荷载作用下的承载力分析.比较整体模型与简化模型的计算结果发现,玻璃板块的存在强化了系统刚度,提高了支承杆件抵抗风荷载的性能.     

基于现场总线技术的水泥旋窑DCS控制系统在我厂的应用

根据淄矿东华水泥公司5000t/d熟料生产线的工艺特点和控制要求,对整个生产控制系统进行了细致的功能分层及子系统的划分;在此基础之上,充分发挥了现场总线技术及DCS技术两者优势,以系统集成为手段,给出一套基于PROFIBUS现场总线协议的旋窑熟料生产线的集散控制系统(DCS),实现了对熟料生产的集中管理和分散控制。通过近一段时间的实际应用表明,本系统在降低成本、减少维护以及简化管理的同时,极大提高了熟料生产的连续性、稳定性和实时性,在经济及社会效益方面均取得了良好效果。     

俯冲段弹载非理想凝视聚束SAR总体性能分析

讨论了弹载SAR在末制导阶段导弹俯冲飞行时非理想凝视聚束模式SAR的总体性能指标,提出了各指标的分析和计算方法,开发了相应的总体性能分析软件.论文首先阐述了俯冲段弹载SAR的工作机理,在非理想凝视情况下引入混合度的概念,并且分析了不同混合度下的工作模式,提出了非理想凝视聚束SAR在俯冲阶段统一的等效距离模型,给出了系统...     

金属波纹管摩擦损失试验研究

通过现场实测2根27m采用金属波纹管套管的预应力梁的总摩擦损失,根据《混凝土结构设计规范》给出的公式,反推摩擦系数k、μ值,以此来推断张拉过程中k、μ的变化规律,以及《混凝土结构设计规范》给定值的合理性;根据计算分析,总结现场施工时需注意的关键问题。     

横泉水库帷幕灌浆试验点分析

横泉水库工程地质条件复杂,采用帷幕灌浆的方法对风化岩层进行处理以满足水库对防渗要求.风化岩层上为厚度16～30m的覆盖层,覆盖层由土层和砂卵石层组成.主要介绍了深覆盖层下风化基岩帷幕灌浆试验的钻孔、灌浆施工方法及其灌浆效果分析.为风化基岩帷幕灌浆积累了经验,可供同类大型工程帷幕灌浆时参考.     

挖掘机发动机无法启动故障排除

液压挖掘机在使用过程中,经常会遇到启动方面的问题。整机无法启动往往会给机主带来经济损失。本文以一个挖掘机早期故障实例人手,阐述了发动机无法启动的状况,分析其原因并介绍了实施排除故障的方法。     

海水管道系统用大口径S32750超级双相不锈钢焊接管道制造研究

介绍了某核电厂海水管道系统用S32750焊接管道的制造方法,采用等离子弧焊并添加填充金属制造Φ610 mm×6.35 mm管道,可以实现单道次单面焊、双面成型,焊缝质量稳定,提高了生产效率.在不经热处理的情况下,管材的各项性能(拉伸、弯曲、硬度、耐腐蚀等)均能满足标准及一般工况要求,可以避免管材因不恰当的热处理带来的一系列问题.     

Role of molecular structure on bioelectrochemical reduction of mononitrophenols from wastewater

The effect of nitro-substituent on mononitrophenol (o-nitrophenol (ONP), m-nitrophenol (MNP) and p-nitrophenol (PNP)) reduction in a bioelectrochemical system (BES) was investigated in this study. The results show that the removal of all three nitrophenols was significantly enhanced with more negative cathode potential and shortened hydraulic retention time in the BESs. Moreover, the reduction of the three nitrophenols followed in the order of ONP > MNP > PNP in the BESs. Both quantum chemical calculation using density function theory and cyclic voltammetry analysis confirmed the reductive sequence of the three nitrophenols. In addition, the acute toxicity of nitrophenol effluent significantly decreased while its biodegradability was enhanced after treatment in the BES. Therefore, the BES technology offers bright prospects for efficient treatment of nitrophenol-containing wastewater.