基于Fluent的闭合环型缺氧反应器构造优化

为提高闭合环型缺氧反应器混合效果,选用基于Fluent软件的三维RNG k-ε紊流数学模型对闭合环型缺氧反应器进行流场模拟,以池底可能淤积面积比例作为混合效果的评价标准,分别从导流直墙长度、导流墙偏心距离及水下推进器偏置等3个方面对缺氧池的系统构造的最优设置进行研究。结果显示,在相同推进器功率下,导流直墙长度2.0 m为佳,导流墙偏心距离0.5 m为佳,推进器向内偏置0.5 m为佳。该研究方法及其结果可以作为闭合环型缺氧反应器的设计依据,具有较佳的技术参考价值。     

Investigation on the Chemical Structure of Nonextractable Residues of the Fungicide Cyprodinil in Spring Wheat Using 13C-C1-Phenyl-Cyprodinil on 13C-Depleted Plants—An Alternative Approach to Investigate Nonextractable Residues

Abstract

¹³C-labelled cyprodinil was applied on ¹³C-depleted wheat plants with 27-fold field application rate. A control experiment applying same amounts of ¹⁴C-cyprodinil showed that main portions of the residues were detected in the cellulose (15% NER), hemicellulose (28.3% NER), and lignin fraction (23.3% NER). 16.7% were detected in water soluble polymers, 6% in both, pectin and protein fraction, and 4% in the starch containing fraction. Free cyprodinil was detectable by TLC in all fractions except lignin. A direct characterization of the residues in vivo by CP-MAS was not successful. Cell wall fractions were further analysed by liquid state NMR to determine the structure of the mobilized highly polymer/polar residues: Within lignin, where most of the residues were located at field application rate, neither intact cyprodinil nor its metabolites could not be detected. The ¹³C-label introduced was probably incorporated in the polymer as natural lignin monomers and thus are not considered as bound residues according to IUPAC definition.     

Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks

Utilization of construction and demolition (C&D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C&D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates.     

产朊假丝酵母CANDIDA UTILIS细胞壁对铜离子吸附位点的研究

目前认为所有生物大分子都对重金属离子有较强吸附性 ,但某些分子可特异地吸附重金属 ,并介导酵母细胞对重金属的抗性[1] .其中细胞表面的高分子聚合物倍受关注 ,酵母细胞壁约含 4 0种蛋白分子 ,但有关这些蛋白质在对重金属离子吸附中的作用目前还未见报道 .产朊假丝酵母Ｃａｎｄｉｄａｕｔｉｌｉｓ是重要单细胞蛋白生产菌株之一 ,因其营养条件要求不高 ,对工业废水有较强耐受和转化能力而广泛用于生产和研究 .我们观察了产朊假丝酵母细胞与分离纯化的细胞壁对铜离子的吸附能力差异 ,并对细胞壁上重金属离子吸附位点进行了研究 .1　材料与方…     

电动振动台动圈的金属绕线壁筒及其加强环的涡流影响的限制与消除

本文阐述了在电动振动台动圈的金属绕线壁筒及其上下加强环中产生的涡流电流对振动台性能的各种影响,并对其有害影响提出了限制与消除的多种实用方法,且论述了上述各种方法的作用机理.特别是文中提出的"全开槽"的创新解决方案,曾为我国振动试验机制造行业攻克动圈涡流影响的这个共同性的重大技术难关闯出了一条成功之路.虽然此"全开槽"方案的提出已有30多年了,在这期间,世界振动试验机行业已取得了长足的进步,但文中的论点及其实验数据,仍然对当今的电动振动台的研制与生产有着现实的指导意义.与文中所述的第⑤种动圈结构相同的具有上加强环"全开槽"的金属台面部与非金属绕线壁筒组成的两体式动圈骨架结构形式已成为当今国际主流的动圈骨架结构形式,由此可见:"全开槽"的方案无疑是消除涡流有害影响的最有效的途径.     

应变率对钢筋混凝土剪力墙动态性能的影响

采用有限元软件ABAQUS中的显示动力分析模块ABAQUS/Explicit,分别对钢筋混凝土剪力墙准静态和高应变率动力荷载作用下的响应进行了数值模拟;通过比较高应变率与准静态加载下的分析结果,探讨了地震作用下应变率对钢筋混凝土剪力墙动态性能的影响。研究结果表明,受应变率效应的影响,混凝土和钢筋的动态力学行为发生了变化,动力荷载作用下的钢筋混凝土剪力墙的承载能力有一定程度的提高,故在对钢筋混凝土结构进行抗震分析时,应适当考虑应变率效应。     

水井酸处理中排污水水质变化规律

盐酸洗井是增大碳酸盐岩井涌水量的一种有效措施。大量盐酸的广泛应用,严重影响地下水质,必须充分考虑到它带来的环境污染问题。本文对水井经酸处理后排放的污水水质作了监测,进而对水质的变化规律作了研究。     

福建土楼夯土墙风驱雨侵蚀损伤预测研究

世界文化遗产福建土楼地处中国东南沿海,年降雨高达1 600 mm,频繁遭受台风和极端天气袭击,每当台风登陆时,狂风挟着暴雨常常侵蚀危害着土楼建筑,风驱雨冲击侵蚀土楼夯土墙已成为土楼建筑的主要损坏形式。论文通过分析风驱雨作用下雨滴的运动形式及降雨特征,采用CFD数值模拟及风洞试验的方法完成数值风洞准确性模拟,以数值风场为基础加入降雨模型,考虑多种雨强和风速相互组合,分析风驱雨对土楼夯土墙的风雨侵蚀影响,揭示了夯土墙风雨侵蚀的内在规律。并通过当地一份气象统计资料作为算例,预测土楼年平均侵蚀损伤量在0.4~2.6 mm之间,所得结果为土楼的维护加固和开发利用提供了科学依据,也为其他生土建筑研究提供借鉴和参考。     

外立面作用下水平湍流浮力射流火焰的附壁研究

用防火板模拟建筑外立面,设计了可控流速和开口尺寸的气体燃烧器产生水平湍流浮力射流火焰,系统研究了外立面抑制火焰卷吸所导致的水平湍流浮力射流火焰附壁规律。将火焰流场演变分为两个阶段:(1)出口到流场水平动量衰减为零(等价点)的阶段;(2)火焰附壁或不附壁的阶段。其中,火焰附壁与否很大程度上取决于等价点到出口的水平距离LE。通过分析,我们发现雷诺应力是导致流场水平动量衰减和火焰附壁的主要原因。由此,我们基于普朗特混合长度理论推导了雷诺应力的近似表达式并结合动量控制方程,获得了LE与修正弗洛德数Fr*的线性关系,从理论上解释了出口宽高比n(n=B/H,B是开口宽度;H是开口高度)越大,火焰越容易附壁的现象,并确定了不同开口及流速条件下,火焰附壁的临界条件。     

超临界直流电站锅炉水冷壁开裂原因分析及改进措施

本文介绍了超临界直流电站锅炉检验中发现的水冷壁开裂、变形,调风器鳍片烧损变形,集箱管接头角焊缝裂纹,刚性梁固定耳板处拉裂、变形等问题。对产生这些问题的原因进行了分析和研究,认为各水冷壁管子内水汽温度不均匀是造成拉裂、变形的主要原因。针对产生问题的原因,提出要预防此类问题发生就必须控制水冷壁超温和降低水冷壁各管子间温度差。并详细地论述了控制水冷壁超温和降低水冷壁各管子间温度差的八项具体改进措施。