铝合金复合石墨烯薄膜的制备及腐蚀性能研究

为提高铝合金的耐蚀性,对经过二次阳极氧化的铝合金氧化膜进行了石墨烯改性处理,得到了硅烷偶联剂KH550/石墨烯复合薄膜.傅里叶红外光谱仪分析表明,电化学剥离制备的石墨烯经过羟基化处理后再经过KH550改性处理,石墨烯的-COOH与KH550的-NH2发生了缩合反应,说明KH550成功接枝到石墨烯上;该复合膜经过电化学测试后发现,复合膜的腐蚀电流密度明显降低,从阳极氧化膜的3.829×10-4 A/cm2减小到1.325×10-6 A/cm2,而且中性盐雾试验结果(NSS试验)表明,改性后的铝合金阳极氧化石墨烯复合膜耐盐雾时间达到280 h.     

圆形截面柱的振动台试验及分析

进行了圆柱振动台试验,对模型的加速度反应数据进行获取。试验表明,随着地震的加速度峰值的不断增加,圆柱顶部加速度极值不断增加。柱顶的加速度响应有着增大的趋势,且极值比输入的加速度的极值有一定的放大。     

浅谈基层消防队伍一网统管与精准治队

消防救援队伍实施"两严两准"建队制度,队伍管理趋向扁平化、正规化,在日常工作中还存在减负增效不明显、部门间工作存在壁垒等管理中的短板.消防队伍"一网统管"能够打通部门数据壁垒,整合管理资源,线上线下联动,"一网管基层"形成跨部门、跨层级、跨队战运行体系,让管理更加科学化、精细化、智能化,是实现基层队站正规化管理的有效路径.本文根据工作实际,提出基层队站的"一网统管"平台建设思路,实现"实际工作中管用、基层指战员爱用"的应用效果.     

Hydrogen evolution reaction on in-plane platinum and palladium dichalcogenides via single-atom doping

Searching for the catalysts with excellent catalytic activity and high chemical stability is the key to achieve large-scale production of hydrogen (H₂) through hydrogen evolution reaction (HER). Two-dimensional (2D) platinum and palladium dichalcogenides with extraordinary electrical properties have emerged as the potential candidate for HER catalysts. Here, chemical stability, HER electrocatalytic activity, and the origin of improved HER performance of Pt/Pd-based dichalcogenides with single-atom doping (B, C, N, P, Au, Ag, Cu, Co, Fe, Ni, Zn) and vacancies are explored by first-principles calculations. The calculated defect formation energy reveals that most defective structures are thermodynamically stable. Hydrogen evolution performance on basal plane is obviously improved by single-atoms doping and vacancies. Particularly, Zn-doped and Te vacancy PtTe₂ have a ΔG_H value close to zero. Moreover, defect engineering displays a different performance on HER catalytic activity in sulfur group elements, in order of S < Te < Se in Pd-based chalcogenides, and S < Se < Te in Pt-based chalcogenides. The origin of improved hydrogen evolution performance is revealed by electronic structure and charge transfer. Our findings of the highly activating defective systems provide a theoretical basis for HER applications of platinum and palladium dichalcogenides.     

Microstructure Evolution of Ni-Co Alloys During Crystallization and Amorphization Process

Journal of Superconductivity and Novel Magnetism - A molecular dynamics simulation has been conducted in Ni73Co27 and Ni74Co26 alloys during rapid solidification at the cooling rate of...     

高压压气机转子结构设计及改进方法

为提高设计效率并快速得到适于工程应用的高压压气机转子结构，以改型设计方法为基础对某高压压气机转子结构进行了详细设计，同时对结构改进方法进行了一定的探索。采用叶—盘耦合系统循环对称结构算法及整体转子系统二维轴对称结构算法进行强度设计及改进，前轴颈最大应力下降最多达26%；其次进行支承结构设计，计算校核母型机轴承承载能力。结果表明：轴向力安全裕度最小为28%，轴承寿命大于100 000 h；给出2种调整鼠笼厚度的估算方法用以指导三维有限元计算，同时计算得到前支承刚度；通过二维有限元分析模型计算转子的临界转速，仅将后轴承支承位置沿压气机轴线向后移动7.5 mm，全运行工况转速与第2阶临界转速的安全裕度由18.5%提高到21.2%。     

Effects of light-emitting diode illumination on the quality of fresh-cut cherry tomatoes during refrigerated storage

The effects of light-emitting diode (LED) illumination on the quality of fresh-cut cherry tomatoes were investigated. Tomatoes were exposed continuously to red, green, blue and white LED light for 7 days and control samples stored in darkness. Results showed that blue light treatment significantly led to more total soluble solids, lycopene concentration and individual phenolic compounds (chlorogenic acid, caffeic acid, rutin) after 7 days of storage. On day-5, green and blue light-treated tomatoes showed relatively higher firmness than samples treated by other lights and the control. At the early stage of storage, blue light could preserve the fresh flavour of tomatoes compared to other treatments. Overall, the blue light was most effective in the quality preservation of fresh-cut cherry tomatoes and could be used as a novel strategy in the preservation of fresh-cut fruits and vegetables during shelf life.     

The impact of hydrogen refueling station subsidy strategy on China's hydrogen fuel cell vehicle market diffusion

Lack of hydrogen refueling stations (HRSs) has hindered the diffusion of hydrogen fuel cell vehicles (HFCVs) in the Chinese transport market. By combining the agent-based model (ABM) and the experience weighted attraction (EWA) learning algorithm, this paper explores the impact of government subsidy strategy for HRSs on the market diffusion of HFCVs. The actions of the parties (government, HRS planning department and consumers) and their interactions are taken into account. The new model suggests dynamic subsidy mode based on EWA algorithm yields better results than static subsidy mode: HFCV purchases, HRS construction effort, total number of HRSs and expected HRS planning department profits all outperform static data by around 27%. In addition, choosing an appropriate initial subsidy strategy can increase the sales of HFCVs by nearly 40%. Early investment from government to establish initial HRSs can also increase market diffusion efficiency by more than 76.7%.     

Investigating the influence mechanism of hydrogen partial pressure on fracture toughness and fatigue life by in-situ hydrogen permeation

In this work, we investigate the influence mechanism of hydrogen partial pressure on fracture toughness and fatigue life of a high strength pipeline steel. Both fracture toughness test and fatigue life test are carried out under different hydrogen partial pressure. The experimental results show that with the increasing of hydrogen partial pressure, fracture toughness and fatigue life decrease and the decrease trends gradually flatten out. Hydrogen has a larger effect on fatigue life than fracture toughness. Only 3% hydrogen gas can cause a 67.7% decrease of fatigue life. The in-situ hydrogen permeation test is performed respectively in 2 MPa, 5 MPa and 8 MPa hydrogen partial pressure. With the increasing of hydrogen partial pressure, the increase trend of hydrogen permeation current gradually tends to be gentle, which indicates that the hydrogen atoms entering into the material gradually become saturated. This result can be used to clarify the influence mechanism of hydrogen partial pressure on fracture toughness and fatigue life.