Formation mechanism and microhardness characterization of the ultrasonic hardening layer in cementitious materials

Ultrasonic surface treatment (UST) is a novel treatment method to improve the durability of cementitious materials, resulting in the formation of an ultrasonic hardening layer (UHL). The UHL acts as an effective natural coating, offering penetration and erosion protection. However, the formation mechanism and the quantitative characterization of the UHL have not been studied, and the validity of the UST on the top and side surfaces of cementitious materials is still unknown. Therefore, in this study, we investigated and proposed a formation mechanism for the UHL, and defined a transition layer between the UHL and the matrix. We also utilized HV microhardness testing to provide an effective quantitative characterization method for the UHL. Finally, using a set of custom-designed ultrasonic molds, we confirmed the validity of the UST on the top and side surfaces of the cementitious materials.     

高铝粉煤灰提取氧化铝过程中镓的转化规律研究

研究了镓在高铝粉煤灰提取氧化铝工艺中的迁移转化规律。在主要生产流程中设置取样点,对镓的富集分布情况进行检测分析。结果表明:高铝粉煤灰中的镓有75%进入成品氢氧化铝,碳循环母液中镓的富集浓度最高,达到46.0 mg/L。     

Towards optimization of functionalized single-walled carbon nanotubes adhering with poly(3-hexylthiophene) for highly efficient polymer solar cells

In this paper, we present the optimization of single-walled carbon nanotubes (SWCNTs) by acid-treatment, solution ultrasonication time and dispersion in photoactive layer for efficient organic solar cells. After non-covalently adhering with poly(3-hexylthiophene) (P3HT), pre-functionalized SWCNTs were blended into the composites of P3HT and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as photoactive layer, and a maximum power conversion efficiency (PCE) of 3.02% with a short-circuit current density of 11.46 mA/cm² was obtained from photovoltaic cell indium-tin oxide (ITO)/poly(ethylene-dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)/P3HT:PCBM:SWCNTs/Al with an optimum 0.3 wt% SWCNTs in P3HT:PCBM:SWCNTs nanocomposite, the PCE can be enhanced by more than 10% as compared to the control device ITO/PEDOT:PSS/P3HT:PCBM/Al. The performance improvement by incorporating with functionalized SWCNTs is mainly attributed to the extension of excitons dissociation area and fastening charge carriers transfer across the active layer.     

界面设计影响蒙汉用户视觉注意的脑电研究

目的 比较蒙、汉用户在不同界面布局的条件刺激下视觉注意对脑电刺激诱发响应的调节和影响作用。方法 基于Oddball实验范式的事件相关电位技术,采用图文形式和纯文本形式的宫格式、标签式,以及侧面展开式界面布局刺激,结合分析脑电数据和行为数据,探究界面布局设计对蒙、汉用户视觉注意的影响。结果 对视觉注意的早期阶段进行研究后发现,图文形式宫格式布局对汉族用户的视觉注意具有显著的刺激和调节作用,而图文形式侧面展开式布局对蒙古族双语用户的视觉注意有显著的刺激和调节作用。通过P300成分波幅发现蒙、汉用户的情绪发生变化,蒙、汉用户在纯文本形式标签式布局界面的影响下产生消极情绪,波幅降低。结论 在事件相关电位技术中,通过P100成分与P300成分的波幅强度变化,可以作为界面布局刺激条件下衡量比较不同民族地区用户视觉注意与情感体验的观测量。     

高柔性聚乳酸薄膜的制备及对口蘑的保鲜效果

目的 为了改善聚L-乳酸(PLLA)的柔韧性和气体选择透过性,将聚富马酸二元醇酯(PNF)作为柔性链段以熔融共聚方式引入PLLA中对其进行改性。方法 以PLLA为主体,加入PNF,并改变其中二元醇链段长度制备一系列聚乳酸-共富马酸二元醇酯(PLNF)共聚物,随后将其制备成薄膜,测试其力学性能、气体透过性能和水蒸气透过性,并对口蘑进行贮藏试验。结果 PNF的加入使PLLA的力学性能、气体选择透过性及透湿性均得到改善,且断裂伸长率是随着二元醇链段的增长而逐渐增大。与PLLA相比,聚乳酸-共富马酸癸二醇酯(PLDF)的断裂伸长率可达346.4%,聚乳酸-共富马酸丁二醇酯(PLBF)的CO2/O2选择透过比从3.0升高到4.4,且在口蘑贮藏期间可维持其形态,呈现较好的感官品质,在15 d内仍具食用价值。结论 PNF的引入有效改善了PLLA的性能,延长了口蘑的货架期,为PLLA薄膜进一步用于生鲜果蔬包装提供了参考。     

曲面零件拉深筋的数值模拟

在拉深筋成形能力理论、曲面零件变形计算结果、以及实际板料参数这3种条件的基础上,以拉深筋参数设置为重点,应用有限元分析软件Dynaform,分别在有拉深筋和无拉深筋这两种条件下,对曲面零件进行有限元模拟实验.通过模拟实验对比的结果,显示了拉深筋在曲面零件变形时的作用,使理论计算和模拟实验得到了相互验证.同时,也进行了实验验证,实验结果与计算机数值模拟结果相吻合.此方法在整个加工工艺工程中简便直观,对于实际生产有一定的推广应用价值.     

Effect of coal type on the flash pyrolysis of various coals

The effect of coal rank on the product distribution pattern was investigated in Ar at 1037 K with a Curie-point pyrolyser, using seventeen coals ranging from lignite to anthracite. The yields of inorganic gases, hydrocarbon gases, light hydrocarbon liquids and tar were determined and correlated with the structural parameters of the coals. The yields of CO₂ were found to have a linear relationship with the carboxylic group content of the coals. The amounts of light hydrocarbon gases correlated well with the aliphatic hydrocarbon content of the coals.     

220 kV变电站智能化改造技术要点及方案实施

杜尔伯特220 kV数字化变电站升级改造为智能变电站.一次设备中,将原电子互感器改造为新型电子互感器配合合并单元的模式.二次设备中,将原有监控系统更换为一体化监控系统;保护及安全自动装置利用了近年新扩建的两套线路,同时将对侧装置软硬件升级为与本侧同版本的保护,利用软件保护定值或算法完成补偿;其余线路保护、主变压器保护、...     

挤压温度对铝合金内螺纹管管壁组织的影响

内螺纹管主要由两部分组成,管壁和内螺纹齿部位,其成形后的质量及换热性能不仅与螺纹齿的质量有关,也与管壁的成形质量有关,并且微观组织的不同也将影响挤压后管材的质量和性能。为成形出高质量的内螺纹管,本文在常用挤压方法的基础上结合金属挤压理论,提出了运用螺纹模芯结合无缝圆管工模具挤压成形铝合金内螺纹管的方法,并利用电子背散射衍射(EBSD)技术分析了挤压温度(420～480℃)对铝合金内螺纹管管壁组织演变的影响。研究表明：在100 mm/min的恒定挤压速度下,随着挤压温度的逐渐升高,管壁横、纵截面的平均晶粒尺寸逐渐增大,分别由420℃的10.5和8.3μm增大至480℃时的18.1和11.6μm;管壁横截面组织主要为周向带状晶,纵截面组织主要为轴向带状晶。对成形后管壁织构的分析表明,随着挤压温度的逐渐升高,管壁变形织构增强,再结晶组织逐渐增多。     

楔横轧成形25CrMo4厚壁空心轴件的不圆度分析

机械结构轻量化的主要途径是在结构上采用空心轴.近年来, 采用楔横轧带芯棒轧制空心轴类件的工艺得到了较广泛的关注.厚壁空心轴类件在楔横轧轧制过程中易发生“失圆”现象.本文通过热压缩实验研究了25CrMo4合金钢在楔横轧变形条件下热变形行为, 获得其真应力-应变曲线.在此基础上, 基于Deform-3D有限元软件, 建立25CrMo4厚壁空心轴楔横轧有限元仿真模型, 分析厚壁空心轴楔横轧成形机理, 研究得出断面收缩率、成形角、展宽角对轧件不圆度的影响规律: 断面收缩率增大, 不圆度减小; 成形角增大不圆度减小, 轧制温度越高减小趋势越明显; 展宽角增大不圆度增大, 提高轧制温度抑制增大趋势.选取部分工艺参数进行楔横轧验证实验, 对比了有限元仿真结果和实验结果, 表明有限元仿真模型预测精度较高.