Structural Aspects of P2-Type Na0.67Mn0.6Ni0.2Li0.2O2 (MNL) Stabilization by Lithium Defects as a Cathode Material for Sodium-Ion Batteries

A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na_0.67Mn_0.6Ni_0.2Li_0.2O₂ is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g^-1 after 100 cycles. In contrast, the Li-free compositions Na_0.67Mn_0.6Ni_0.4O₂ and Na_0.67Mn_0.8Ni_0.2O₂ show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni³⁺/Ni⁴⁺ and O^2-/O^2-δ redox processes by DFT, although a small contribution from Mn⁴⁺/Mn⁵⁺ to the capacity cannot be excluded.     

室内机组的开发与应用

随着市场的发展,精品超市和改造店铺逐渐增多,需要一种更加适合的制冷机组来满足市场的需求。本文提供了一种新型的解决方案,解决了现有机组存在的高噪音和高成本问题,不仅提高了制冷效率,而且节约能源,保护环境。     

A computer aided design method for car form and its application based on shape parameters

In the early design stage, automotive modeling should both meet the requirements of aesthetics and engineering. Therefore, a vehicle CAD (computer aided design) model that can be easily adjusted by feedbacks is necessary. Based on CE-Bézier surface, this paper presents a set of algorithms for parametric segmentation and fairing surface generation in a car model. This model is defined by a simplified automotive template and relevant control points, shape parameters and segmentation parameters, which can be modified to alter the car form efficiently. With this model and the corresponding adjustment method, more than fifty various vehicle models are established in this research according to different parameters. And two methods for calculating similarity index between car models are constructed, which are suitable for brand design trend analysis and modelling design decisionmaking.     

红枣多糖提取、分离纯化及生物活性研究进展

红枣作为我国传统的药食同源的天然保健果品,已有近四千多年的栽植和食用历史。红枣多糖是一种复合杂多糖,现代药理学研究表明多糖是红枣果中主要的功能活性成分之一,具有抗氧化、抗肿瘤、免疫保肝及调节肠道菌群等功能。本文系统地综述了国内外近年来关于红枣多糖提取、分离纯化、结构特征及生物活性的研究进展,以期为提高红枣多糖的利用以及为进一步深入研究红枣多糖构效关系提供理论依据。     

服装新产品市场测试进展

在综合分析研究现状的基础上，以国内的服装行业为研究背景，探讨服装新产品的市场测试方案，文中提出一种基于商店聚类分析的测试方法.     

三峡三期工程大坝混凝土内部温度控制

三峡右岸三期工程施工中,为了有效控制坝体混凝土内部温升,采取了预冷混凝土浇筑、控制混凝土出机口温度及入仓温度,对混凝土内部通水初冷、中冷和后冷等措施,大坝混凝土内部温度没有出现超标现象,混凝土温控工作取得了良好的效果。     

Ru的添加量对FeMn尖晶石的结构 及其氧化性能的影响

 考察了随着FeMn尖晶石催化剂中Ru的添加量的变化以及助剂Cu的加入，催化剂物理结构及化学性质的变化。结果表明，Cu的添加不仅对催化剂的比表面和孔径分布有较大的影响，还对各元素的化学环境有较大的影响。当n(Ru)/n(Mn)为0.05时，由于尚未破坏尖晶石的结构，Ru的存在对于催化剂中其它元素如Mn、Fe和O的化学环境具有较大的影响，当n(Ru)/n(Mn)大于0.15时，尖晶石结构被破坏，Ru含量的增加对于其它元素如Mn、Fe和O的化学环境影响不大，对于比表面积和孔径分布等物理性质也影响很小。所研究的催化剂均可催化氧化醇至醛或酮，Ru的含量越大，催化醇液相氧化性能越好。     

微型轴流风扇噪声特性分析及试验研究

本文对微型轴流风扇噪声的产生机理进行了系统分析及教育处，并进行了实验测试。得出的分析计算结果与实验数据作了比较验证，在声压随观测角度和距离的变化关系上，两者显示出基本一致的趋势。文中以等流量为前提，对降低微型风扇噪声的一种途径作了计算，结果表明采用转轴很细的风扇，可使噪声明显降低（大于3dB）。     

折边锥形封头厚度计算探讨

分析了GB 150-1998《钢制压力容器》中圆筒和折边锥形封头大端的厚度计算公式,认为计算折边锥形封头的厚度时,可只考虑与过渡段相接处的锥壳厚度。