Preparation and electrochemical properties of La–Mg–Ni-based La0.75Mg0.25Ni3.3Co0.5 multiphase hydrogen storage alloy as negative material of Ni/MH battery

La–Mg–Ni-based La_0.75Mg_0.25Ni_3.3Co_0.5 hydrogen storage alloy was synthesized by high-energy mechanical milling blending of the La_0.75Ni_3.3Co_0.5 as-cast alloy prepared by vacuum arc melting and elemental Mg, and subsequent isothermal annealing. The chemical compositions, microstructures and electrochemical properties of the as-cast La_0.75Ni_3.3Co_0.5 alloy, the milled and annealed La_0.75Mg_0.25Ni_3.3Co_0.5 alloys were investigated, respectively, by inductively coupled plasma, X-ray diffraction, differential scanning calorimetry, X-ray photoelectron spectroscopy and electrochemical measurements. The results show that single LaNi₅ phase exists in the as-cast La_0.75Ni_3.3Co_0.5 alloy. The milled La_0.75Mg_0.25Ni_3.3Co_0.5 alloy contains multiphase structure, besides the main LaNi₅ phase, a small amount of (La,Mg)Ni₃ and (La,Mg)₂Ni₇ new phases are observed as well. The annealed La_0.75Mg_0.25Ni_3.3Co_0.5 alloy is composed of LaNi₅ and (La,Mg)₂Ni₇ phases. Annealing treatment can result in (La,Mg)Ni₃ phase converting into (La,Mg)₂Ni₇ phase. The electrochemical measurements indicate that the maximum discharge capacity and discharge potential characteristic of the as-cast La_0.75Ni_3.3Co_0.5 alloy are better than those of the milled La_0.75Mg_0.25Ni_3.3Co_0.5 alloy, whereas worse than those of the annealed La_0.75Mg_0.25Ni_3.3Co_0.5 alloy. The cyclic stability of the milled La_0.75Mg_0.25Ni_3.3Co_0.5 alloy is slightly better than that of the as-cast La_0.75Ni_3.3Co_0.5 alloy, whereas obviously worse than that of the annealed La_0.75Mg_0.25Ni_3.3Co_0.5 alloy. Overall, the annealed La_0.75Mg_0.25Ni_3.3Co_0.5 alloy performs the best in the maximum discharge capacity, discharge potential characteristic and cycling stability.     

均聚和共聚聚丙烯树脂在改性方面性能差异研究

对均聚聚丙烯和共聚聚丙烯在热氧老化、耐应力发白、着色性以及不同条件处理后收缩率方面差异进行了研究。结果表明,经过150℃热氧老化后,均聚聚丙烯冲击性能下降严重,而共聚聚丙烯的冲击性能先上升至200 ％以上,然后缓慢下降;树脂结晶度越高,越规整或无规整,乙烯含量越低,耐应力发白性能越好;热处理及水煮后,聚丙烯结晶度越高,后收缩率越小;熔体流动速率越大、结晶越容易,黑度越大、色相越偏蓝。     

Dissociation characteristics of methane hydrate using depressurization combined with thermal stimulation

Methane hydrate is considered as a potential energy source in the future due to its abundant reserves and high energy density. To investigate the influence of initial hydrate saturation, production pressure, and the temperature of thermal stimulation on gas production rate and cumulative gas production percentage, we conducted the methane hydrate dissociation experiments using depressurization, thermal stimulation and a combination of two methods in this study. It is found that when the gas production pressures are the same, the higher the hydrate initial saturation, the greater change in hydrate reservoir temperature. Therefore, it is easier to appear the phenomenon of icing and hydrate reformation when the hydrate saturation is higher. For example, the reservoir temperature dropped to below zero in depressurization process when the hydrate saturation was about 37%. However, the same phenomenon didn't appear as the saturation was about 12%. This may be due to more free gas in the reservoir with hydrate saturated of 37%. We also find that the temperature variation of reservoir can be reduced effectively by combination of depressurization and thermal stimulation method. And the average gas production rate is highest with combined method in the experiments. When the pressure of gas production is 2 MPa, compared with depressurization, the average of gas production can increase 54% when the combined method is used. The efficiency of gas production is very low when thermal stimulation was used alone. When the temperature of thermal stimulation is 11 °C, the average rate of gas production in the experiment of thermal stimulation is less than 1/3 of that in the experiment of the combined method.     

空间分类数据同位规则挖掘算法

针对空间分类数据的特性,提出一种空间分类数据同位规则挖掘算法．利用空间关系定义数据挖掘中事务的概念,采用多层参与索引搜索空间同位规则,从而实现了对空间分类数据的有效处理．采用文中算法对杭州地区119火灾数据进行实验,并验证了该算法的适用范围和性能．实验表明,该算法可以有效地处理经过离散化后的连续数据．     

Microstructure morphologies of asphalt binders using atomic force microscopy

We investigated microstructure morphologies of three asphalts (SK, Karamay, and Esso) used in China using atomic force microscopy (AFM). The topography and phase contrast images were obtained. Topographic profile and three dimensional images were described. Roughnesses of microstructure were calculated. And the chemical compositions of asphalt were tested to explain the microstructural mechanism of the asphalt. The results show that the topography and phase image in atomic force microscopy are appropriate to evaluate the microstructure of the asphalt binder. There are significant differences in microstructural morphologies including bee-like structure, topographic profile, 3D image, and roughness for three asphalts in this study. There are three different phases in microstructure of asphalt binder. The oil source and chemical composition of asphalt, especially asphaltenes content have a great influence on the microstructure.     

巴润矿矿岩混合复杂爆区爆破分离技术试验研究

巴润矿床成因复杂,矿体不规整、产状及空间形态无规律,爆区内常出现多矿种、众矿体和多岩性混合的矿岩分布状态。常规露天开采爆破过程使破碎矿(岩)石在爆堆中相互混合,导致矿石贫化、损失较严重。针对矿岩混合复杂爆区存在的矿体边界不清、爆破过程矿岩混合和电铲装车时难以直观辨识矿(岩)石等难题,提出了向矿(岩)体中部抛掷堆聚、矿(岩)体交界处爆破分离成清晰沟槽为核心的分离爆破技术方案。通过钻孔岩粉取样化验圈定爆区内矿(岩)体的实际边界,综合应用矿(岩)体中部等时线定向抛掷堆聚技术、矿(岩)体边界多自由面长延时对孔起爆抛掷分离技术和电子雷管精准起爆技术等,实现了爆破荷载作用下矿(岩)石有序堆聚和边界清晰分离的目标。基于颗粒流PFC3D的数值模拟研究初步确定了台阶深孔爆破矿岩分离的技术参数,在此基础上开展了现场爆破分离试验。现场爆破试验的台阶高度为14 m,炮孔直径为310 mm,孔排距为(8～10) m×6 m,采用三角形布孔方式。先行起爆紧邻矿岩分界的同排两侧炮孔,延时110 ms后同时起爆跨矿岩边界的同排两侧炮孔。爆区内以矿(岩)体中部为起爆零点的多"V"型精准起爆和等时线抛掷堆聚等技术的综合应...     

排水孔布设参数对降雨边坡稳定性的影响

针对降雨入渗导致的边坡失稳这一安全问题,以巴润露天矿边坡为研究对象,探究降雨入渗条件下排 水孔布设参数对边坡稳定性的影响。 采用空气单元法模拟排水孔,基于 VG 模型确定水土特征曲线,运用 Geo-studio 软件进行数值模拟分析。 基于灰色关联法确定排水孔布设参数对边坡稳定性影响的关联度,分析单一变量条件下坡 体内孔隙水压力和总水头变化,在此基础上通过正交试验和极差分析法对布设参数进行优化,确定排水孔布设参数 最优水平组合。 最后通过对比无治水措施边坡与布设排水孔边坡的稳定性,验证降雨条件下排水孔布设方案的有效 性。 结果表明:排水孔孔长为主要影响因素,孔径和倾角为次要影响因素;孔长 10 m、孔径 120 mm 和倾角 6°时,排水 孔对边坡降压增稳效果最好;在经历 48 h 降雨情况下边坡安全系数仍保持在 1. 30 以上,相较于无治水措施边坡安全 系数提高了 36. 8%。     

保压时间对储氢合金电极电化学性能的影响

在不同保压时间下制备Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3储氢合金电极,研究保压时间对合金电极的活化性能、最大放电容量、放电特性和循环稳定性的影响规律和机制。结果表明,保压时间对合金电极的活化性能基本无影响。合金电极的其它电化学性能随保压时间的增加均呈现出先变好后变坏的变化规律,保压时间为15min时,合金展示了最佳的综合电化学性能,电化学性能的改善主要归因于合金电极的电荷转移速度加速和内阻减小。     

保压时间对储氢合金电极电化学性能的影响

在不同保压时间下制备了Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3储氢合金电极,研究了保压时间对合金电极的活化性能、最大放电容量、放电特性和循环稳定性的影响规律和机制。结果表明,保压时间对合金电极的活化性能基本无影响,而合金电极的其他电化学性能随着保压时间的增大均呈现出先变好后变坏的变化规律,保压时间为15min时,合金展示了最佳的综合电化学性能,电化学性能的改善主要归因于合金电极的电荷转移速度加速和内阻减小。     

工艺参数对铝镁搅拌摩擦焊焊缝成形质量的影响

工艺参数对铝镁异种材料搅拌摩擦焊接头质量有着重要影响,研究了焊接速度,搅拌头旋转频率,材料放置位置,搅拌头正反转及偏移等工艺参数对7075铝合金与AZ31B热挤压态镁合金异种材料搅拌摩擦焊对接接头成形质量的影响.结果表明,在搅拌针旋转频率为13 r/s,焊接速度为30 mm/min下可获得较好的焊缝成形质量;另外,要获...