碳基薄膜在航空轴承乏油问题中的应用研究

目的 研究乏油工况下GLC和DLC两种碳膜在航空轴承上的应用。方法通过磁控溅射技术在单晶硅片P(100)、轴承钢样块和轴承套圈表面分别制备了GLC和DLC两种薄膜。利用扫描电镜（SEM）、拉曼光谱对薄膜的截面和磨痕形貌及结构进行了分析。利用纳米压痕仪、摩擦磨损试验机等对薄膜的力学性能和摩擦学性能进行了研究。利用轴承试验机对镀两种膜的轴承进行了对比研究。结果 GLC和DLC两种碳基薄膜均结构致密,GLC薄膜含有更多的sp2,DLC薄膜含有更多的sp3;两种薄膜硬度分别达到18.2 GPa和22.2 GPa,弹性模量分别达到230.2 GPa和260.8 GPa,干摩擦条件下,薄膜摩擦系数分别低至0.11和0.21。镀膜轴承在运转0~10 h时,温升无明显差异;10~30 h过程中,镀GLC薄膜轴承温升约为40~45 ℃,而镀DLC薄膜轴承温升约为50~55 ℃。运转后,轴承滚子上出现转移膜,镀GLC薄膜的轴承磨损比镀DLC薄膜的轴承严重。结论 在乏油工况下,DLC薄膜具有更加优异的环境适应性。     

织构化热处理对钢轨钢耐磨性和寿命的影响

目的减小钢轨钢表面因离散硬化产生的硬化区与基材边界处的硬度突变,从而消除磨损过程中硬化区与基材边界处因材质不连续而产生的早期碎裂现象,进一步提高钢轨钢的耐磨性和寿命。方法提出了一种基于层流等离子体束离散硬化的表面织构化热处理方法。与之前的离散圆点状硬化不同,通过调节等离子体束在试样表面的运动速度,改变试样表面的加热时间,在硬化区与基材之间人为地附加了一个过渡区。为了揭示织构化热处理对钢轨钢滚滑性能的影响,在摩擦磨损试验机上进行了磨损试验。磨损后的试样经切割、打磨、抛光和腐蚀,在光学显微镜和扫描电子显微镜下进行了观察,以分析试样的磨损过程和织构化热处理提高试样耐磨性的机理。结果由于附加过渡区的存在,相变区的一边被拉长,形状变为泪滴状。硬化区到基材的硬度变化率由3500 HV/mm降低至200 HV/mm,在圆点状硬化中可观察到的硬度突变消失。同时,在磨损实验中,泪滴状硬化试样的磨损量较圆点状硬化试样降低了27%,边界碎裂消失。结论具有附加过渡区的试样比圆点状硬化的试样具有更好的耐磨性和抗塑性变形能力,该方法对提高钢轨钢的使用寿命具有一定的应用前景。     

快速成型中STL模型直接切片新算法研究

提出基于快速成型中STL模型直接切片新算法。读取二进制STL模型信息,创建三角面片矩阵;采用二分查找算法实现三角面片与切平面相交分组;再对每一组中三角面片与相交切平面求其交点获得相交线段,去除相交线段间的冗余节点;最后用深度优先搜索算法对切平面中相交线段优化创建轮廓线路径。此算法避免了切平面与三角面片位置关系的判断和建立三角面片之间拓扑信息关系,在切片耗时上具有明显的优势。     

供油量对浮环轴承静动态润滑特性影响

针对浮环轴承贫油润滑问题,基于雷诺方程,建立浮环轴承贫油润滑模型,以润滑油入口供油量为可变参数,通过有限差分法求解数学模型,分析了供油量对浮环轴承内外油膜力静态润滑特性影响,计算结果表明:供油量明显影响润滑油油膜力的起始角和轴承环速比,摩擦功耗随浮环轴承供油量的减小而增大。     

变量齿轮泵的新机制研究与微圆槽的卸荷能力分析

为实现功率和排量的同步变化以节省资源,提出一款齿轮泵变量的新机构,该机构原理简单,由变量弹簧力和高压油压力的动态平衡驱动齿轮副有效啮合宽度的自动变化,从而实现泵功率和排量随有效啮合宽度的同步变化;并就其困油性能与困油卸荷进行深入研究和分析,提出具有微圆结构的卸荷槽;最后,进行实例运算和分析。结果表明:微圆卸荷槽具有更大的卸荷面积和卸荷能力;有效啮合宽度越小,困油压力峰值越小,困油性能越好;反之,困油性能越差,但影响不大。     

Comparison of particle-phase polycyclic aromatic hydrocarbons and their variability causes in the ambient air in Ho Chi Minh City, Vietnam and in Osaka, Japan, during 2005-2006

A comparative study of polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter (TSP) in the ambient air in an urban area in Ho Chi Minh City, Vietnam and in Osaka, Japan was carried out from 2005 to 2006. The objective of this study was to investigate the environmental levels, emission sources, seasonal variations and health risk of eleven PAHs in the two cities, especially Ho Chi Minh City where air pollution is becoming a serious concern. The results showed that the concentrations of TSP and total PAHs were significantly higher in Ho Chi Minh City than levels in Osaka. The concentrations of 5- and 6-ring PAHs (BeP, BbF, BkF, BaP, BghiP and InP) were much higher in TSP samples in Ho Chi Minh City than in Osaka, accounting for 82% and 51% of total PAHs, respectively. These PAHs are known to be highly carcinogenic and mutagenic in humans. Vehicular emission is suggested as one of the main pollution sources of PAHs in both cities. Motorcycles and gasoline automobiles are suggested as the main emission sources of PAHs in Ho Chi Minh City, whereas diesel automobiles are the primary source in Osaka. Seasonal variations of PAHs were observed in this study; higher concentrations of PAHs were found in the rainy season (May-December) and lower concentrations corresponded to the dry season (February-April) in Ho Chi Minh City, while higher concentrations of PAHs were observed in the winter (November-January) in Osaka. The number of sunshine hours was an important meteorological factor affecting seasonal variations of PAHs in Ho Chi Minh City, while the temperature was a main factor causing the variations of PAHs in Osaka. The high BaP equivalent concentration of 5- and 6-ring PAHs even in the ambient air is an alarming signal for harmfulness to human health and environmental quality in Ho Chi Minh City.     

预应力新技术在翠林大桥中的应用

翠林大桥为福建省厦漳高速公路上的重要桥梁，同时跨越翠林河和漳龙公路。桥型为五孔连续预应力混凝土箱梁桥，桥梁全长为２３５．４０ｍ，桥面全宽为２６．０ｍ，按汽车－超２０级、挂车－１２０荷载标准设计。本文着重介绍翠林大桥设计中国内首次应用的全断面同步张拉施工法、新型ＣＤＭ大吨位镦头锚体系，以及大直径（φ２２００ｍｍ）预应力混凝土空心管桩基础等新技术。     

Mobilization of adsorbed copper and lead from naturally aged soil by bacterial extracellular polymers

Sorption of pollutants is a dominant phase transfer process affecting the fate and transport of metals through the subsurface. The movement of contaminants is retarded by sorption to the stationary subsurface porous media and can seriously hinder remediation efforts. Research has shown that the binding of adsorbed metals becomes more pronounced the longer the contaminant is in the subsurface and the release rates of aged metal contaminants have not received the research attention given to freshly added metals in laboratory studies. Metal release rates are also influenced by the presence of dissolved ligands that compete with mineral soil surfaces by providing binding sites. Dissolved organic matter such as bacterial extracellular polymers are common in natural soil solutions and the metal binding properties of bacterial polymers are well established. Therefore, binding of metals to dissolved biopolymers may result in mobilization of an adsorbed metal. This is important for cases where the metals are assumed to be relatively immobile such as in the case of land applied biosolids. In addition, naturally occurring adherent bacteria commonly produce extracellular polymers and thus may modify the bioavailability of meal contaminants at the point of their attachment. In this study samples from three sites, one a land applied sludge test site, were used to investigate the ability of bacterial extracellular polymers to release metals from soils with long-term exposures. The presence of ?200mg/L bacterial extracellular polymer was found to increase the short-term (less than 350h) release of Cu and Pb by a factor of 2-4-fold.     

高效滤纸测试方法的研究

通过钠焰法、油雾法、DOP法、最易透过粒径法等滤纸测试方法的对比,阐明滤纸测试方法发展的趋势。     

Hydrogen and methane production from household solid waste in the two-stage fermentation process

A two-stage process combined hydrogen and methane production from household solid waste was demonstrated working successfully. The yield of 43 mL H(2)/g volatile solid (VS) added was generated in the first hydrogen production stage and the methane production in the second stage was 500 mL CH(4)/g VS added. This figure was 21% higher than the methane yield from the one-stage process, which was run as control. Sparging of the hydrogen reactor with methane gas resulted in doubling of the hydrogen production. pH was observed as a key factor affecting fermentation pathway in hydrogen production stage. The optimum pH range for hydrogen production in this system was in the range from 5 to 5.5. The short hydraulic retention time (2 days) applied in the first stage was enough to separate acidogenesis from methanogenesis. No additional control for preventing methanogenesis in the first stage was necessary. Furthermore, this study also provided direct evidence in the dynamic fermentation process that, hydrogen production increase was reflected by acetate to butyrate ratio increase in liquid phase.