Surface energies in high-entropy carbides with variable carbon stoichiometry

The carbon vacancy in high-entropy carbides (HECs) has a significant impact on their physical and chemical properties, yet relevant studies have still been relatively few. In this study, we investigate the surface energies of HECs with variable carbon vacancies through first-principles calculations. The results show that the surface energy of the (1 0 0) surface of the stoichiometric HECs is significantly lower than that of (1 1 1) surface. With the decrease in carbon stoichiometry, the surface energies of both (1 0 0) and (1 1 1) surfaces increase gradually, which is mainly due to the weakening of covalent bonding and the decrease of metal Hirshfeld-I (HI) charges. However, the surface energy of (1 0 0) surface increases more quickly than that of (1 1 1) surface and will exceed that of (1 1 1) surface when the carbon stoichiometry decreases to a certain extent, which is primarily attributed to the greater decrease rate of metal HI charges of (1 0 0) surface.     

云制造环境下人力资源需求的评价与选择方法

为了解决云制造环境下人力资源提供方对需求方的选择问题,以人力资源提供方的视角,提出一种基于需求方的需求能力和偏好符合度的评价与选择方法。首先,构建了对需求方需求能力的评价指标体系,结合变精度粗糙模型,求得各候选需求方的需求能力;其次,由提供方的供给偏好,计算出各候选需求方的偏好符合度;然后根据各候选需求方的需求能力以及偏好符合度求解其各自的综合需求价值,从而为提供方对需求方的选择提供重要参考依据;最后,以实例验证了该方法的有效性。     

Total Focusing Method Approach of Ultrasonic Phased Array Based on Compressed Sensing

Russian Journal of Nondestructive Testing - Nondestructive testing and evaluation technology of the total focusing method (TFM) based on full matrix capture (FMC) is a hot spot in the current array...     

Influence of Wheel Blunting on the Machining Precision in CNC Plunge Grinding: Digital Twin Analysis

Russian Engineering Research - The machining precision in grinding a flexible shaft by sharp and blunt wheels is compared for a CNC system with a specified cycle of radial supply velocities. To...     

Energy Conservation at High-Tech Enterprises by Means of Automated Energy Management

Russian Engineering Research - Practical approaches are described for introducing an energy management system at a high-tech enterprise so as to centralize and automate the regulation of energy...     

Controlled fabrication of Pr(OH)3 nanowires for enhanced photocatalytic activities

In this report, praseodymium hydroxide Pr(OH)₃ nanowires with different aspect ratios (length to diameter ratios) were synthesized by a facile hydrothermal approach. The variations in alkali concentration during synthesis are found to form different aspect ratios of nanowires. The X-ray diffraction and Raman spectroscopy analysis demonstrate the absence of any impurity phases in as-prepared materials. Subsequently, photocatalytic activities of as-prepared nanowires were evaluated by the degradation of methyl orange (MO). Our findings reveal that the nanowires with larger aspect ratios have higher photocatalytic efficiency than the smaller aspect ratio samples. X-ray photospectroscopy investigations reveal that the samples with higher aspect ratio are found to exhibit more oxygen vacancies as compared to lower aspect ratio samples. The enhanced photocatalytic activities can be attributed to the presence of higher percentage of active crystal facet (100), higher concentration of defects densities and narrower band gap. Thus, Pr(OH)₃ nanowires can be considered as a potential candidate for the application of wastewater treatment and related technologies.     

Short-Term Creep of St3 Steel Under Low-Frequency Cyclic Loading

Strength of Materials - Creep constitutive equations have been derived for the materials that exhibit the properties of orthotropy (transversal isotropy) and transient creep under cyclic loading. A...     

Study of the Effect of Composition and Thermal Deformation Treatment on Properties of Ferritic Steels Microalloyed with Titanium and Niobium. Part 2. Phase Precipitate Characteristics*

Metallurgist - The effect of composition and thermal deformation treatment parameters (temperature for the end of rolling and strip winding on a coil, cooling rate after rolling) on mechanical...     

气瓶内部淬火过程的流动换热特性

 大直径厚壁气瓶内部淬火时的流动换热过程极其复杂，受到多种因素的影响，而研究气瓶内部压强和温度的变化规律对改善流动换热效果、提高产品组织性能具有重要的理论指导意义。以914 mm厚壁气瓶和瓶内流体为研究对象，建立了二维等效流 固耦合模型；采用多喷嘴系统对气瓶内外进行喷水淬火，研究了气瓶总长、喷水流速及淬火时间对瓶内压强及内壁温度的影响，通过间歇淬火试验验证了数学模型的正确性。结果发现，气瓶长度对瓶内压强和瓶壁温度的影响显著，喷水流速次之，当喷水流速大于8 m/s后，水量对瓶壁的冷却效果大大降低；气瓶内壁长度方向的温度梯度分别随气瓶总长的增加和淬火时间的延长而减小，但基本不受喷水量的影响。