三峡二期工程施工及关键性技术

本文重点介绍了混凝土生产与温度控制、金属结构及机电设备等施工情况和关键性技术。三峡工期工程需浇筑混凝土1846万m~3,安装金属结构及机电设备埋件19.2万t,施工工期6年。     

弯螺杆钻具力学特性分析与设计

设计或选择弯螺杆钻具组合时，既要确定弯螺杆钻具的总体方案结构参数，还要预测该钻具组合的造科能力。利用结构弯角的等效角和等效横向载荷，推导了用以分析具有结构弯角的螺杆钻具组合力学特性的三弯矩方程组，并应用它确定钻具组合的平衡曲率。根据实钻结果研究了弯螺杆钻具组合造斜能力与平衡曲率间的关系，得出了平衡曲率系数的数学表达式，并将其应用于φ39．7mm套管侧钻水平井的φ89mm弯螺杆钻具总体方案设计。计算表明，这种φ89弯螺杆钻具应设计成传动轴本体上带有稳定器的单弯钻具。     

梁桥恒载跨中挠度允许值[f_t]确定

长期以来,我国桥规对梁桥恒载跨中挠度允许值[ft]空缺;一般均用活载挠度fp=[L/600]来代替。经过近20年研究,认为这是造成中国P.C连续梁跨中普遍下挠、底板开裂的一个重要原因。通过论文分析,提出设计应控制合拢前初始挠度[f]≤L/4800才能确保桥梁安全。     

不同预处理方式与微滤联用处理城市污水对比实验研究

采用微滤法处理模拟二沉池出水,以期达到城市污水回用的目的.进水采用人工配水,主要考察微滤膜对模拟二沉池出水中CODMn,氨氮(NH3-N)及UV254的去除效果,以及预处理方式对微滤膜处理工艺的影响.实验主要采用了两种预处理方式,即颗粒活性炭(GAC)吸附及聚合氯化铝(PAC)混凝.实验结果表明,单独采用微滤膜效果不明显,高锰酸钾指数的去除率仅为32.5%,氨氯去除率约为5%,且膜污染严重,通量下降很快.活性炭-微滤组合工艺对污水的CODMn去除效果较好,去除率达到88%;而混凝-徽滤工艺对UV254的去除效果较好,去除率达到87%;混凝-微滤及活性炭-微滤工艺对氨氮的去除率均不高.组合工艺比起单独使用微滤膜流量下降缓慢,混凝-徽滤工艺在4.5h内,流量没有下降,污染情况明显改善.     

任意移动载荷作用于梁上的弯矩研究

通过对作用于梁上的任意移动载荷引起的弯矩计算的研究，推导出不需对任意移动载荷进行假设和简化处理即可准确地计算出弯矩的新计算方法，比现已知的国内外同类问题的计算更科学和准确。     

Cycle characterizations of LiMxMn2−xO4 (M=Co, Ni) materials for lithium secondary battery at wide voltage region

LiM_xMn_2−xO₄ (M=Co, Ni) materials have been synthesized by a melt-impregnation method using γ-MnOOH as the manganese source. Highly crystallized LiM_xMn_2−xO₄ compounds were synthesized at a calcination temperature of 800°C for 24 h in air. All compounds show a single phase except for LiNi_0.5Mn_1.5O₄ based on the X-ray diffraction (XRD) diagram. With the increase of the doping content from 0.1 to 0.5, the capacity of doping materials decreases mainly in the 4 V region.

Although LiM_0.5Mn_1.5O₄ (M=Co, Ni) compound shows a small capacity in the (3+4) V region compared with parent LiMn₂O₄, it is a very effective material in reducing capacity loss in the 3 V region that is caused by the Jahn–Teller distortion. The doping of Co and Ni ions in the LiMn₂O₄ cathode material promotes the stability of this structure and provides an excellent cyclability.     

关于预应力混凝土结构设计规范若干问题的建议

作者在预应力混凝土工程施工实践及理论分析的基础上，对现有预应力混凝土结构技术规程中有关次内力及摩擦、锚固损失的计算问题提出了进一步完善的建议。     

永磁直线同步电动机的绕组型式

介绍了永磁直线同步电机定位力和低速力矩波动的产生原因以及解决方法,分析了多种绕组型式克服低速力矩波动和定位力方面的优缺点.     

Effect of secondary air supply rate on the combustion of volatile gas in a controlled‐air incinerator

Experiments have been carried out to study the effect of secondary air supply rate on the combustion of volatile gas in a controlled‐air incinerator. The secondary air supply was varied at flow rates of 0.56, 1.026, 1.73 Nm³/min. The waste in this study was categorized into three types: namely those containing low, medium and high combustible matter. The significant results of the experimental investigation shown that increasing secondary air supply rate reduces the chamber temperature in both chambers and strong effect on CO reduction for waste with high combustible content. NO formation increases slightly as secondary air supply increases and SO₂ formation depends on the sulfur content in the waste and insensitive to secondary air for the range of flow rate tested. Copyright © 2005 John Wiley & Sons, Ltd.     

Monitoring the oxidation of unsaturated oils and formation of oxygenated aldehydes by proton NMR

The oxidation process of rapeseed, walnut and linseed oils, rich sources of linolenic acyl groups, was studied by means of ¹H nuclear magnetic resonance spectroscopy. The visible changes in some spectrum signals, especially in those of methylic, allylic and bis‐allylic hydrogen atoms, provide information about the degradation of the different acyl groups throughout the oxidation process. The rate of the changes produced in the three oils was compared, not only in relation to the rate of degradation of the different acyl groups, but also to both the formation and degradation of primary as well as to the formation of secondary oxidation products. Among the secondary oxidation products, the study was focused on the formation of aldehydes, their nature and evolution throughout the oxidation process of these three oils. The formation of n‐alkanals, trans‐2‐alkenals, trans,trans‐2,4‐alkadienals, as well as of the well known geno‐ and cytotoxic 4,5‐epoxy‐, 4‐hydroperoxy‐ and 4‐hydroxy‐trans‐2‐alkenals, was proved to take place.