基于遗传算法的行星轮减速器优化

遗传算法可以通过模拟自然进化的过程来搜索最优解,只需目标函数及适应度函数,不需要依赖梯度或其它辅助信息,多用于函数优化、组合优化、生产调度、自动控制、机器人学、图像处理、遗传编程等诸多方面。文中利用遗传算法对行星轮减速器进行了多目标函数的遗传算法优化分析。     

航天工况下滚珠丝杠副的有限元分析

结合航天工况下滚珠丝杠副的国内外研究状况,建立了滚珠与螺母滚道及丝杠滚道的分析简化模型和接触有限元模型.基于ABAQUS隐式动力学,对滚珠丝杠副的接触变形进行弹塑性仿真,用有限元接触分析结果验证了分析简化模型的合理性,具有一定的理论价值和重要意义.     

Contact and friction between catheter and blood vessel

Therapeutic vascular catheterization techniques are sometimes hampered by the frictional forces between the blood vessel and the catheter, when contact points of the vessel are changing and deforming during the movement of the catheter. The goal of the present study was to characterize frictional interactions between the blood vessel wall and the catheter using experimental and numerical analysis. First, the frictional force was measured with an experimental apparatus that uses a ball and flattened porcine aorta to simulate frictional forces between the catheter and the vessel. Second, catheter motion was characterized by two-dimensional numerical calculations based on the experimental results. Experimental analysis demonstrated that slip occurred and that friction coefficient between the vessel and the catheter and the deformation of the specimen were small when the contact between the ball and the aorta occurred at a small angle. The compliance of the specimen in the normal direction obtained by the experiment was by far larger than that calculated according to the Hertzian contact theory. Numerical analysis shows that this difference of the parameter of the vessel, which must be determined accurately in surgical simulator, could affect the trajectory of the catheter.     

突发性水污染事故的应急处理

近年来，我国城市水源地突发性污染事件日益增加，如何保护水源地生态环境安全和城市供水系统安全，以及如何快速、有效地处理突发性水污染事故已成为亟需解决的问题。介绍了突发性水污染事故应急处理的一般程序，重点讨论了应急措施、处理技术及区域污染物的处理方法。对于危及城市自来水厂区域的突发性污染事故，若在其处理能力范围内，可采用强化混凝、三级处理、备用水源地取水、开启与邻近城市间的备用供水管网等应急处理方法向城市供水；对于自来水厂取水口等遭受污染的水域，可采用吸附、化学沉淀、化学氧化、强化消毒等方法对不同污染物进行治理或隔离。     

Stormwater runoff quality and quantity from asphalt, paver, and crushed stone driveways in Connecticut

This study compared the quality and quantity of stormwater runoff from replicated asphalt, permeable paver, and crushed-stone driveways. Rainfall was measured on-site and runoff was recorded using tipping buckets. Flow-weighted composite runoff samples were analyzed weekly for total suspended solids, total Kjeldahl nitrogen, nitrate-nitrogen, ammonia-nitrogen, total phosphorus (TP), zinc, lead, and copper. Infiltration rate was determined on each driveway annually. Repeated measures analysis of variance indicated that stormwater runoff was significantly different among each driveway type; the order of decreasing runoff was asphalt> paver> stone. Average infiltration rates were 0, 11.2 and 9.0 cm/h for asphalt, paver, and crushed stone driveways, respectively. Both paver and crushed stone driveways reduced stormwater runoff as compared to asphalt driveways. Runoff from paver driveways contained significantly lower concentrations of all pollutants measured than runoff from asphalt driveways. However, runoff from crushed stone driveways was similar in concentrations to runoff from asphalt driveways, except for TP concentrations, which were lower in runoff from crushed stone driveways than runoff from asphalt driveways. The mass export of measured pollutants followed the relative differences in stormwater runoff, rather than differences in concentrations.     

浅议城中村建筑和规划的现状与未来

面对在中国城市普遍存在“城中村”的现象,调查了“城中村”目前的人居现状及人居环境中存在的大量问题,提出改造城中村的思路与模式,揭示“城中村”实现合理城市化的重要意义。     

管理优化技术在施工中的应用

介绍了优化技术的三要素，以及管理优化技术的方法类型，以满约束条件的极值法为例，分析了围墙最优参数和桁架最优参数的确定方法，指出建立管理优化技术对于建筑施工实现目标最优值，具有指导作用。     

某金矿尾矿库土壤污染现状调查及发展趋势分析

对某金属矿尾矿库流域内的土壤、植物等进行调查取样,确定尾矿库对周边环境的污染范围和污染趋势,对尾矿库所在流域的污染程度、污染特征等进行评价与分析,探明尾矿库是否对周边及下游植物造成严重污染。研究结果表明,该尾矿库的土壤砷元素含量超标严重,总氰化物、锑、镉、汞、锌元素含量也略有超标,尾矿库流域的污染区以尾矿库为中心,向周边由近及远污染程度递减;尾矿库的周边植物样品中各检测元素含量均未超标,可以推测尾矿库尚未对周边及下游植物造成严重污染。这些分析可以为其它尾矿库污染方面的研究提供依据。     

安徽淮北市青东煤矿8-2煤层顶板冲击倾向性鉴定条件分析

安徽省淮北市青东煤矿是华东腹地最重要的矿集区之一, 其煤种具有良好的结焦性能。通过现场勘查、地表填图和物探测量等工作手段, 以及运用Surfer、AutoCAD等软件作图分析, 赋值叠加计算并制作煤层真厚度的等值线图、坚硬岩层钻孔分布图和需开展冲击倾向性鉴定区域图。青东矿8-2煤层埋深超过400 m的煤层约占总体的80%, 单层厚度超过10 m的坚硬岩层主要分布在矿井的西南、东北和中部偏南方向;西十采区的南部、西八采区的中部以及8725工作面整体和Ⅱ872工作面东部等地需要做冲击倾向性鉴定。冲击倾向性鉴定条件的分析, 为青东矿的安全开采提供理论支持和有力保障。     

贵州遵义松林地区土壤地球化学特征及其生态环境评价

贵州遵义松林地区华南下寒武统黑色页岩 Ni-Mo 矿化带土壤质量评价具有重要的科学及实际意义。以松林土壤为研究对象,采用 ICP-MS 方法分析其中23个元素的含量,分析结果显示具有高镉、砷、汞含量特征。运用地质累积指数和潜在生态风险指数分别对土壤镉、砷污染程度和潜在生态风险进行评价,评价结果表明:遵义松林土壤已遭受镉、砷相对较高程度的污染；该区土壤镉、砷具有较高潜在生态风险,值得进一步的土壤污染修复研究,以期为土地资源管护、农业结构的调整和特色山地农业的发展及永久基本农田划定提供科技支撑。