Influence of alumina on mineralogy and environmental properties of zinc-copper smelting slags

An iron-silicate slag, from a zinc-copper smelting process, and mixtures of this slag with 5wt%, 10wt%, and 15wt% alumina addition were re-melted, semi-rapidly solidified, and characterized using scanning electron microscopy equipped with energy dispersive spectroscopy, and X-ray diffraction. The FactSageTM6.2 thermodynamic package was applied to compare the stable phases at equilibrium conditions with experimental characterization. A standard European leaching test was also carried out for all samples to investigate the changes in leaching behaviour because of the addition of alumina. Results show that the commonly reported phases for slags from copper and zinc production processes (olivine, pyroxene, and spinel) are the major constituents of the current samples. A correlation can be seen between mineralogical characteristics and leaching behaviours. The sample with 10wt% alumina addition, which contains high amounts of spinels and lower amounts of the other soluble phases, shows the lowest leachabilities for most of the elements.     

Mechanical properties of directionally solidified lead-antimony alloys

The Pb-17wt% Sb alloy was directionally solidified under two solidification conditions: with different temperature gradients (G=0.93–3.67 K/mm) at a constant growth rate (V=17.50 μm/s) and with different growth rates (V=8.3–497 μm/s) at a constant temperature gradient (G=3.67 K/mm) in a Bridgman furnace. Microstructure parameters, such as primary dendrite arm spacing (λ₁), secondary dendrite arm spacing (λ₂), and dendrite tip radius (R), were measured. The microhardness (Hv) and ultimate tensile strength (σ) of the directional solidification samples were also measured. The influences of solidification and microstructure parameters on Hv and σ were investigated. The results obtained in this work were compared with similar experimental researches in literatures. It is shown that the Hv and σ values increase with the increase of G and V, but decrease with the increase of λ₁, λ₂, and R.     

Optical properties of cobalt xanthate films on different substrates

Cobalt isopropyl xanthate thin films (CXTFs) were deposited via chemical bath deposition onto different substrates: commercial glass (CG), indium tin oxide (ITO), and poly(methyl methacrylate) (PMM). Isopropyl xanthate was synthesized according to a method described in the literature. The cobalt nitrate and isopropyl xanthate were mixed in a beaker, which allowed the thin films to be deposited via a simple ion-ion mechanism. The transmission, reflectivity, refractive index, dielectric constant, and optical conductivity were investigated for various thin films coated onto different substrates. An ultraviolet-visible spectrophotometer was used to measure the optical properties of the thin films. The lowest value of the transmission and the highest value of the refractive index were observed for the thin films deposited onto PMM. The structure of the cobalt xanthate was characterized by Fourier transform infrared (FTIR) spectroscopy, which was measured using a Perkin-Elmer Spectrum 400 spectrometer. The stretching vibration of the Co-S bonds was observed at 359 cm-1 in the FTIR spectrum of the CXTFs.     

基于质量预测的飞机装配动态调度问题研究

为提高飞机装配调度计划应对装配质量不合格的能力,首先以两阶段近似动态决策为框架,研究装配质量与相关因素的映射关系和不确定性因素在不同决策周期的表现形式,并以最小化基于场景的项目工期期望值为目标函数建立整数规划模型;然后基于构建的飞机装配质量预测模型,设计了多层循环迭代搜索算法,算法第一层基于任务列表的编码方式优化任务执行顺序,第二层通过装配人员分配列表优化人员配置,第三层根据人员配置结果求解目标函数. 数值实验结果显示在工件质量预测值与实际值不一致的情况下,多层循环迭代搜索算法在任务开始时间偏差能够保持在2以下,表明该算法能够适应不确定性因素的变化,满足构建飞机装配动态调度计划的需求.     

异构分布式环境中的并行离群点检测算法

离群点检测是数据挖掘领域研究的热点之一,主要目的是识别出数据集中异常但有价值的数据点. 随着数据规模不断扩大,使得处理海量数据的效率降低,随即引入分布式算法. 目前现有的分布式算法大都用于解决同构分布式的处理环境,但在实际应用中,由于参与分布式计算的处理机配置的差异,现有的分布式离群点检测算法不能很好地适用于异构分布式环境. 针对上述问题,本文提出一种面向异构分布式环境的离群点检测算法. 首先提出基于网格的动态数据划分方法（Gird-based Dynamic Data Partitioning,GDDP）,充分利用各处理机的计算资源,同时根据数据点的空间位置信息进行数据划分,可有效减少网络通信. 其次基于GDDP算法,提出了异构分布式环境中并行的离群点检测算法（GDDP-based Outlier Detection Algorithm,GODA）. 该算法包括2个阶段：在每个处理机本地,按照索引中数据点的顺序进行过滤,通过2次扫描得到离群点候选集;判断候选离群点需要进行网络通信的处理机,使用较低网络开销得出全局离群点. 最后,通过大量实验验证了本文提出的GDDP和GODA算法的有效性.     

NiTiNb-SMA丝主动加固RC圆柱抗震性能试验

为研究国产镍钛铌形状记忆合金(NiTiNb-SMA)丝主动约束加固钢筋混凝土墩柱的抗震性能,完成了3个墩柱试件的拟静力试验.基于试验现象和水平力-位移曲线,对比分析了各试件的骨架曲线、承载力和延性、强度退化、累计耗能、残余位移等性能指标.结果表明:热激励NiTiNb-SMA丝能有效地为墩柱提供主动约束应力,减轻墩柱的损伤,并提高墩柱的延性和耗能能力,对比原试件,NiTiNb-SMA丝对试件主动加固后的位移延性系数和累计耗能分别提高了27.8%和10.4%;有效减缓了墩柱的强度衰减,减小了墩柱的残余位移.     

两嵌段共聚物在扁长形受限空间的相行为研究

应用自洽场方法模拟计算了本体结构为柱状相的AB两嵌段共聚物在球形和扁长形三维受限空间下的自组装行为.通过改变受限空间的尺寸,系统总结了AB两嵌段共聚物在球形和扁长形受限下的相形态、自由能、构象熵和相互作用能的变化规律并做了比较研究.结果表明,在受限体系中,嵌段共聚物会呈现出多样的相形态;在球形受限中,嵌段共聚物的相形态由于在不同方向上受限程度相同而表现出较好的结构对称性;而在扁长形受限中,共聚物分子链在不同维度方向上会受到不同程度的伸展取向限制,从而其相结构的对称性会被破坏.     

结构动力时程分析的地震动选择方法研究

进行结构动力时程分析时,合理地选择地震动一直是工程中的难点问题.为此,通过改进现有的和声搜索法进行地震动的选取,针对依据我国现规范设计的两榀不同周期的预应力混凝土(PC)框架结构进行了动力时程分析,并与周期点法、双频段法和面积法的计算结果进行对比.分析表明:多遇地震作用下,周期点法和改进的和声搜索法的结构响应参数的离散性更小,其变异系数在10%左右,且与振型分解反应谱法得到的底部剪力相比,双频段法和改进的和声搜索法得到的计算结果更加符合规范设计水准;罕遇地震作用下,面积法和改进的和声搜索法的结构响应参数的离散性更小,其变异系数在15%左右,周期点法计算结果离散性最大;周期点法只适用于弹性时程分析的地震动选择过程,改进的和声搜索法无论是对弹性时程分析还是弹塑性时程分析都适用,且满足规范设计水准和工程需求.     

国产结构用铝合金断裂韧性参数校准

为了将空穴增长模型(VGM)和应力修正临界应变模型(SMCS)应用于国产结构用铝合金的韧性断裂预测,完成了国产6061-T6、6082-T6和7020-T6 3种牌号的铝合金标准圆棒试件和缺口圆棒试件的单轴拉伸试验,并结合有限元分析,校准了3种牌号铝合金的VGM和SMCS模型断裂韧性参数.研究结果表明:槽口半径大小对各牌号铝合金试件的断裂韧性参数校准值影响较小,离散系数均在20%以内;断裂韧性参数是铝合金材料固有属性,可用于国产结构用铝合金在不同应力状态下的韧性断裂预测;与SMCS模型相比,VGM模型能够更为精确地预测铝合金材料的韧性断裂.     

基于改进多目标布谷鸟搜索算法的 汽车装配线物料配送调度

考虑将电动车辆用来进行基于点对点配送策略的汽车装配线的物料配送,提出了改进多目标布谷鸟搜索算法. 首先,对该物料配送调度问题进行描述,在统筹考虑电量限制和准时化配送要求的基础上建立了以车辆数量和最长搬运时间作为衡量指标的目标函数,并开发了直接反映配送车辆和配送次序的融合编码机制. 然后,设计任务分配规则构造初始解,并在基于混沌动态步长的搜索过程中加入高斯变异和精英选择策略来提高算法的全局搜索能力和解的质量. 此外,开发两种局部搜索算子以强化算法深度寻优能力. 最后,仿真实验结果验证了该调度算法的可行性和有效性.