管桩地基顶升复位的试验研究

本文结合某实际工程,研究和开发了地基处理新技术——桩式托换和柱基顶升复位。文中对这种新方法的可行性进行了论证,给出了合理的施工方案和托换的基本原则;结合压桩过程,对静压钢管桩的沉桩机理、阻力特性,以及钢管桩的闭塞效应对单桩承载力的影响进行了理论分析和探讨,得出了一般规律;在现场单桩静载试验的基础上,讨论了单桩的极限承载力和容许承载力,给出了容许承载力的取值方法;通过实测桩身的应变,得出了单桩轴向力和摩阻力的分布规律;文中还研究了厂房整体空间效应对顶升的影响,给出了预估荷载时采用的空间效应系数的建议值。实践证明,本方法适合于产生了较大不均匀沉降或倾斜的建(构)筑物的地基事故处理。     

齿轮磨损量与滑动系数优化设计的探讨

本文论证了利用齿轮磨损量计算式与滑动系数计算式进行优化的结果的一致性。为了减少齿轮的磨损,采用滑动系数计算式进行优化较为简便。笔者利用最优化方法,建立了满足渐开线圆柱齿轮传动在滑动系数相等等条件下的变位系数优化选择的数学模型。编制了计算机程序并进行了运算、获得了满意的设计效果。     

桩基瞬态动测的理论与应用

瞬态动测法试桩有参数动测法、反射波法、机械阻抗法及共振法等等方法。动测试桩分桩身质量检测和单桩承载力测定两部分,前者基于波在介质分界面的反射原理,由反射类型判断桩身缺陷形式;后者则根据线性振动的理论,由经验公式估算。     

钙铝质矿相对碱激发矿渣氯离子固化能力的影响研究

本文提出了一类改性碱激发矿渣胶凝材料,通过在原材料中掺入额外的钙、铝质矿相(Ca(OH)₂和γ-Al₂O₃),促进材料基体中的Friedel's盐(F盐)在氯离子存在条件下的形成,进而提升胶凝材料的氯离子固化能力。本研究探讨了钙、铝质矿物含量对碱矿渣反应产物组成、氯离子固化量以及力学性能的影响。结果表明,钙、铝质矿相的额外补充可显著提高胶凝材料的氯离子固化能力,同时体系的m(Ca)/m(Al)与该能力的相关性较高。物相分析结果表明,钙质矿相的补充使得反应产物中拥有富余的Ca(OH)₂,在氯盐侵蚀作用下,富余的Ca(OH)₂全部转化为F盐或其他物相,证实了体系氯离子固化能力的增强得益于F盐的形成,即得益于化学固氯能力的提升。抗压强度测试结果,表明钙质矿物的掺入对力学性能存在一定负面影响,而铝质矿相的掺入则能够在一定程度上弥补强度损失。     

微孔节流气体静压止推轴承跨缝过程时变特性研究

目前,大型气浮平台均采用花岗岩平台拼接而成,平台拼缝会对实验效果产生一定影响。针对上述问题,以微孔节流气体静压轴承运动中经过平台拼缝时的时变特性为研究对象,建立微孔节流止推轴承物理模型,并使用CFD软件与UDF相结合的动网格技术实现轴承跨越平台拼缝的动态过程仿真,研究不同气膜厚度、进气口压力、平台拼缝位置对轴承承载力和压力分布的影响。结果表明：当平台拼缝到达微孔分布圆附近时承载力急速下降,且平台拼缝到达轴承中心时承载力下降到最小值;随着气膜厚度的增加,轴承承载力的最大损失比例随之增加,并最终稳定到0.6;平台拼缝位于供气孔分布圆之外时,轴承边缘与平台拼缝之间的承载面将失效;通过增加进气口压力,轴承承载力整体有明显提升,但承载力损失速度也明显加快。     

Electrochemical hydrogen storage performance of as-cast and as-spun RE-Mg-Ni-Co-Al-based alloys applied to Ni/MH battery

The La-Mg-Ni-Co-Al-based AB₂-type La_0.8–xCe_0.2Y_xMgNi_3.4Co_0.4Al_0.1 (x=0, 0.05, 0.1, 0.15, 0.2) alloys were prepared via melt spinning. The analyses of the X-ray diffraction (XRD) and scanning electron microscopy (SEM) proved that the experimental alloys contain the main phase LaMgNi₄ and the second phase LaNi₅. Increasing Y content and spinning rate lead to grain refinement and obvious change of the phase abundance without changing phase composition. Y substitution for La and melt spinning make the life-span of the alloys improved remarkably, which is attributed to the improvement of anti-oxidation, anti-pulverization and anti-corrosion abilities. In addition, the discharge capacity visibly decreases with increasing the Y content, while it firstly increases and then decreases with increasing spinning rate. The electrochemical kinetics increases to the optimum performance and then reduces with increasing spinning rate. Moreover, all the alloys achieve to the highest discharge capacities just at the initial cycle without activation.     

铸管厂球墨铸铁管烘干炉技术改造

随着铸管机的生产能力从14万吨增加到20万吨,烘干炉已不能满足生产与工艺要求,铸管出炉温度只有40℃左右,无法烘干固化表面防腐层,导致表面质量较差。在减少投资和运营成本的前提下,对烘干炉的燃烧系统、热风循环系统、控制系统进行改造。在不改变炉体整体结构与尺寸的情况下,把原有加热与循环系统分离的方式改为加热循环一体式。热风系统由原来的从头部到尾部的大循环方式改为上下对吹,中部回风的方式,提高风速及对流换热系数,使炉温从50℃升高到了100℃,铸管出炉温度达60℃以上,保证了扩能后的生产能力。     

A novel method for preparing LiFePO4 nanorods as a cathode material for lithium-ion power batteries

An effective method for synthesizing a one-dimensional nanostructure to improve the rate performance of LiFePO₄ as the cathode material for Li-ion power batteries is described. The crystal structure, composition, and morphology of the prepared LiFePO₄ were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), respectively. The reaction mechanism of the LiFePO₄ nanorods is discussed herein. Electrodes consisting of the LiFePO₄ nanorods have better rate discharge capacities over a potential range of 2.5-4.2 V (vs. Li⁺/Li). These results are attributed to the shorter distance of electron transport and the fact that ion diffusion in the electrode material is limited by the nanorod radius. Our results indicate that the prepared LiFePO₄ nanorods are promising cathode materials for Li-ion power batteries. This new process for synthesizing nanorod products from nanorod raw material can be extended to the preparation of other one-dimensional materials.     

Friction stir welding of aircraft wings

ABSTRACT

To reduce the weight of the wings of the TU-204SM aircraft, investigations were carried out to design the upper wing panel made of the V-1469 high-strength aluminium–lithium alloy of the third generation. The technology of friction stir welding was developed and fragments of the welded panel produced. The tests of the stability under compression showed that the application of the welded panels reduces the weight of the wing by up to ~10% and increases the stability and load carrying capacity by up to ~30%.     

高比容量镍氢电池的制备及电化学性能

Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.