Operando Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Sodium–Oxygen Redox Reactions

Lower charge overpotential of sodium–oxygen (Na–O₂) batteries makes them a promising electrical storage technology. However, they have an undesirable discharge product, sodium carbonate (Na₂CO₃), which has widely been found in many previous studies. Whether and how the carbon components in the cathode are involved in the formation of Na₂CO₃ is still not well understood. Herein, an all solid-state Na–O₂ battery was constructed and its charge and discharge cycles were studied using ambient pressure X-ray photoelectron spectroscopy. The operando XPS results clearly demonstrate the formation of Na₂CO₃ on the cathode during the discharge cycle. A fraction of the carbonate formed can be cycled while charging the battery. Transformation of the carbon-based cathode to Na₂CO₃ is a potential cause of capacity fading of the Na–O₂ battery.     

再加工工艺对N18锆合金板残余应力的影响

采用“热轧+冷轧+退火”工艺对N18锆合金板进行再加工,通过X射线法分析板的表面残余应力,采用EBSD技术分析晶界取向差角分布和大小角度晶界。结果表明,热轧后N18锆合金板的表面残余应力呈现无规律分布状态;冷轧后板的表面残余应力均为压应力,其大小随着冷轧变形量的增加而增加;退火后板的表面残余应力值处于较低水平,当退火制度为500 ℃×2 h时,残余应力处于最低水平;退火后,板的微观结构以小角度晶界为主,且随着退火温度的升高,小角度晶界的密度先增加后趋于稳定。     

A transient fluid–structure interaction analysis strategy and validation of a pressurized reactor with regard to loss-of-coolant accidents

Nuclear Science and Techniques - Rare event search experiments are one of the most important topics in the field of fundamental physics, and high-purity germanium (HPGe) detectors with an ultra-low...     

基于大数据分析的分布式MOLAP技术研究

在计算机系统运行以及研究环节中,会存在大量的规模效应,此类状况难以避免,要想有效解决此类问题,就需要利用分布式的处理方式,开展对文件系统的分析。文章对分布式多维联机分析过程(MOLAP)的数据模型进行了分析,从维编码的算法、映射归约(MapReduce)算法的实现、分析维的遍历算法等方面作深入探讨。     

基于CFD-DEM方法的净化器流场模拟与结构优化

针对空气净化器能耗高的问题，使用离散元方法(DEM)在吸附滤网中建立随机堆积柱形活性炭模型，采用计算流体力学(CFD)方法对空气净化器内部流场进行数值模拟，在模拟与实验验证的基础上，考察了压降最小、流场最均匀的吸附滤网结构。结果表明，空气净化器压降主要发生在轴向，活性炭吸附滤网中回流、沟流现象严重，流体阻力是其他两种滤网的3倍。边数对多边形填充孔结构吸附滤网内压降与流场均匀性无影响，当孔结构改为圆形时，压降减小约52 Pa，节能18.4%(49 W)；当孔直径由8 mm增至12 mm，压降减小约48 Pa，节能19.4%(45 W)；滤网间距对空气净化器压降无影响，圆形、小孔径的吸附滤网内流场最均匀。     

激光散射法测定大方无烟煤粒度的测试条件的选择

利用激光粒度分布仪对大方无烟煤进行了测试，目的是为了选取测量过程中最佳测试条件。结果发现测试条件对试验结果的影响较大，特别是分散剂、超声时间、搅拌池泵转速对测试结果的影响尤为显著。最终确定了激光粒度分布仪测试样品的合理测试条件，即分散剂为无水乙醇，无烟煤折射率为1.66，吸收率为0.46，在搅拌池中的超声时间为180 s，搅拌池泵转速为1 600 r·min^-1。另外，取样方法中，试管法和四分法均具有良好的代表性。     

Optimal design of Raman fibre amplifier based on terminal value optimization strategy and shuffled frog leaping algorithm

This paper introduces an evolutionary algorithm, Shuffled Frog Leaping Algorithm (SFLA), to solve the optimization problem in designing the multi-pumped Raman Fibre Amplifier (RFA). SFLA is a powerful optimizer tool because of its efficient mathematical expressions and global search capability. We utilize SFLA to determine the optimal pump wavelengths and pump powers by minimizing the gain ripple of RFA. To accelerate calculations, a terminal value optimization strategy (TVOS) is incorporated into the evolution of SFLA. This proposed strategy takes the terminal power values of pumps as the decision variables in optimization. Then, the optimal original power values of the pumps are obtained by solving the Power Coupled Equations once, without using the traditional method of repetitive guesses.The combination of SFLA and TVOS enhances the efficiency of optimization and accelerates calculation, while satisfying the design requirements of RFA.The simulation results show that nearly 65% of computational time has been saved compared with the traditional average power analysis. The 4-pumped C+L band of backward multi-pumped RFA with the average net gain of 0 dB, 1 dB and 2 dB are designed individually, where the gain ripple is less than 0.64 dB. The combination of SFLA and TVOS enhance the optimization efficiency and improve the performance of RFA with good gain profile.     

MSCT多期增强扫描在肾脏透明细胞癌中的诊断价值

目的探讨多排螺旋CT(MSCT)多期增强扫描在肾脏透明细胞癌诊断中的规律性,提高对该肿瘤诊断水平。方法回顾性分析2016年1月~2018年6月14例均经手术切除病理证实为肾脏透明细胞癌患者的CT影像资料,所有病例均行MSCT平扫及多期动态增强扫描。结果14例肾脏透明细胞癌形态大多数呈圆形或者类圆形,瘤体最大径范围1.7cm^11.3cm,平均(4.8±1.4)cm,13例CT平扫时肿瘤密度不均匀,呈等低密度,1例呈等密度;12例出现坏死囊变,钙化1例,伴肾盂、肾盏侵犯2例;动态增强扫描可见12例包膜完整,1例均匀性强化,13例不均匀性强化;引入对比剂后皮质期,出现10例病灶强化幅度大于肾皮质,而仅4例低于肾皮质,三期平均CT值分别为110±30Hu,90±15Hu及75±14Hu,其中在实质期出现13例肿瘤强化幅度小于肾实质,仅1例大于肾实质。结论引入对比剂动态增强扫描后,肾脏透明细胞癌在皮质期明显不均匀强化,实质期强化幅度下降显著,呈现出典型的“快进快出”血流动力学强化方式,且肿瘤容易出现坏死、囊变为其特点。