热氧处理条件对聚丙烯粉料DSC曲线形态的影响

发现热氧处理条件对聚丙烯粉料DSC曲线的形态变化有很大影响。随着热氧处理时间的延长,聚丙烯粉料的第一次升温熔融曲线和第二次升温熔融曲线的熔融峰温都会逐渐下降(左移)。第一次升温熔融曲线的熔融峰宽逐渐变窄,峰高逐渐变高;而第二次升温熔融曲线却熔融峰宽逐渐变宽,峰高逐渐变低。在热氧处理时间为0.5~5 h之间时,第一次升温熔融曲线会出现一个很宽的平台状小熔融峰,当热氧处理时间为12 h和14 h时,第二次升温熔融曲线的孪生双峰最明显。随着热氧处理时间的延长,聚丙烯粉料结晶峰温呈现向较低温(向左)方向移动的趋势。     

Discovery of Superconductivity in 2M WS2 with Possible Topological Surface States

Recently the metastable 1T′‐type VIB‐group transition metal dichalcogenides (TMDs) have attracted extensive attention due to their rich and intriguing physical properties, including superconductivity, valleytronics physics, and topological physics. Here, a new layered WS₂ dubbed “2M” WS₂, is constructed from 1T′ WS₂ monolayers, is synthesized. Its phase is defined as 2M based on the number of layers in each unit cell and the subordinate crystallographic system. Intrinsic superconductivity is observed in 2M WS₂ with a transition temperature T_c of 8.8 K, which is the highest among TMDs not subject to any fine‐tuning process. Furthermore, the electronic structure of 2M WS₂ is found by Shubnikov–de Haas oscillations and first‐principles calculations to have a strong anisotropy. In addition, topological surface states with a single Dirac cone, protected by topological invariant Z₂, are predicted through first‐principles calculations. These findings reveal that the new 2M WS₂ might be an interesting topological superconductor candidate from the VIB‐group transition metal dichalcogenides.     

Isomer‐Pure Bis‐PCBM‐Assisted Crystal Engineering of Perovskite Solar Cells Showing Excellent Efficiency and Stability

A fullerene derivative (α‐bis‐PCBM) is purified from an as‐produced bis‐phenyl‐C₆₁‐butyric acid methyl ester (bis‐[60]PCBM) isomer mixture by preparative peak‐recycling, high‐performance liquid chromatography, and is employed as a templating agent for solution processing of metal halide perovskite films via an antisolvent method. The resulting α‐bis‐PCBM‐containing perovskite solar cells achieve better stability, efficiency, and reproducibility when compared with analogous cells containing PCBM. α‐bis‐PCBM fills the vacancies and grain boundaries of the perovskite film, enhancing the crystallization of perovskites and addressing the issue of slow electron extraction. In addition, α‐bis‐PCBM resists the ingression of moisture and passivates voids or pinholes generated in the hole‐transporting layer. As a result, a power conversion efficiency (PCE) of 20.8% is obtained, compared with 19.9% by PCBM, and is accompanied by excellent stability under heat and simulated sunlight. The PCE of unsealed devices dropped by less than 10% in ambient air (40% RH) after 44 d at 65 °C, and by 4% after 600 h under continuous full‐sun illumination and maximum power point tracking, respectively.     

基于电路拓扑结构分析的等价性验证方法

随着集成电路设计规模的日益增大,结合多种推理引擎已成为组合电路形式化等价性验证的重要手段.提出一种基于电路拓扑结构分析的组合等价性验证方法,将电路的拓扑结构与验证算法的复杂性关联起来.在验证过程开始之前,利用min-cut方法计算表征电路复杂性的"电路宽度",以确定最佳的推理引擎,避免了传统的引擎切换过程,提高了算法的效率.针对ISCAS85电路的实验结果表明了该方法的效率和可行性.     

EPA实时以太网与标准化

分析了实时以太网研究背景，介绍了EPA实时以太网与标准的技术特点、EPA国家和国际标准化情况，以及EPA标准发展和推广现状。     

高效液相色谱法测定苯杨酚乳油

用高效液相色谱法测定苯甲酸、水杨酸和三唑酮，相对偏差均小于１．５％。     

基于特征融合的风机叶片表面缺陷检测模型

针对风机叶片表面缺陷检测识别率低、且易受光照影响的特点。提出一种基于卷积神经网络特征融合局部二值模式特征及核极限学习机的风机叶片表面缺陷检测方法。利用引入注意力机制的卷积神经网络提取图像深层次信息,然后提取描述图像浅层纹理信息的局部二值模式特征,采用主成分分析方法降低局部二值模式特征维度;将两种从不同层面描述图像的互补特征串行融合。用改进的麻雀搜索算法优化核极限学习机参数,利用融合的特征训练模型,得到最优模型进行缺陷识别。通过实验,在自建数据集训练后的分类准确率达到了97.5%,kappa系数达到95.1。相比利用单一特征检测,分类准确率有明显的提高。经风电场实际验证,本模型的平均分类准确率为96.3%,Kappa系数为94.5,漏报率明显降低。     

现场总线的标准与发展

简要介绍了IEC61158现场总线8个类型的概况,并对各种总线的技术特点和应用领域作了相应的介绍,最后讨论了现场总线的发展情况.     

High N-doped hierarchical porous carbon networks with expanded interlayers for efficient sodium storage

Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate anode materials impedes further applications. Herein, a novel self-template strategy is designed to synthesize uniform flowerlike N-doped hierarchical porous carbon networks (NHPCN) with high content of N (15.31 at.%) assembled by ultrathin nanosheets via a self-synthesized single precursor and subsequent thermal annealing. Relying on the synergetic coordination of benzimidazole and 2-methylimidazole with metal ions to produce a flowerlike network, a self-formed single precursor can be harvested. Due to the structural and compositional advantages, including the high N doping, the expanded interlayer spacing, the ultrathin two-dimensional nano-sized subunits, and the three-dimensional porous network structure, these unique NHPCN flowers deliver ultrahigh reversible capacities of 453.7 mAh·g⁻¹ at 0.1 A·g⁻¹ and 242.5 mAh·g⁻¹ at 1 A·g⁻¹ for 2,500 cycles with exceptional rate capability of 5 A·g⁻¹ with reversible capacities of 201.2 mAh·g⁻¹. The greatly improved sodium storage performance of NHPCN confirms the importance of reasonable engineering and synthesis of hierarchical carbon with unique structures.