Rapid Experimental Screening of High-Entropy Diborides for Superior Oxidation Resistance

Due to the huge composition space, composition screening is of great importance to the optimization of high-entropy diborides (HEBs) with exceptional oxidation resistance. However, related studies are lacking. Here, a novel rapid, effective strategy to fully screen the compositions on the oxidation resistance of HEBs is proposed. Specifically, the synthesis of the equiatomic 1- to 9-cation multicomponent diborides of the IVB, VB, and VIB groups in seconds via an ultrafast ultrahigh-temperature synthesis technique is realized. Subsequently, combined with the thermogravimetric analysis and first-principles calculations, the roles of incorporated elements are systematically explored. The results show that Zr, Cr, Ta, Nb, and W elements are the key to the improved oxidation resistance of HEBs, while Ti, Mo, and V elements are destructive. In particular, the positive roles of metal elements are mainly attributed to the partial dissolution of the generated metal oxides into the generated B₂O₃ glass, which can improve the viscosity of B₂O₃ and thus enhance its high-temperature stability and reduce the oxygen diffusion rate, as confirmed by the first-principles calculations. This study paves a way to rapidly screen the elements in HEBs, which can be a guide for further anti-oxidation designs.     

冰糖红梨酒发酵工艺优化及香气成分分析

为获得冰糖红梨酒最佳发酵工艺,提升红梨附加值,促进其产业化,本文以魏县红梨为主要原料,开发冰糖红梨果酒.在单因素实验的基础上,通过正交试验优化冰糖红梨酒的发酵工艺,并对优化后的冰糖红梨酒风味成分进行分析.结果显示最优发酵条件为:发酵温度19℃,初始糖度18°Brix,酵母接种量0.06％,初始pH4.8,焦亚硫酸钾添加...     

A hybrid flexible gas sensory system with perceptual learning

Imbuing artificial sensory system with intelligence of the biological counterpart is limited by challenges in emulating perceptual learning ability at the device level.In biological systems,stimuli from the surrounding environment are detected,transmitted,and processed by receptor,afferent nerve,and brain,respectively.This process allows the living creatures to identify the potential hazards and improve their adaptability in various environments.Here,inspired by the biological olfaction system,a gas sensory system with perceptual learning is developed.As a proof-of-concept,H2S gas with various concentrations is used as the stimulation and the stimuli will be converted to pulse-like physiological signals in the designed system,which consists of a gas sensor,a flexible oscillator,and a memristor-type artificial synapse.Furthermore,the learning ability is implemented using a supervised learning method based on k-nearest neighbors(KNN)algorithm.The recognition accuracy can be enhanced by repeating training,illustrating a great potential to be used as the neuromorphic sensory system with a learning ability for the applications in robotics.     

Effects of Niobium on the Mechanical Properties and Corrosion Behavior of Simulated Weld HAZ of HSLA Steel

Simulated microstructures of the TZ, ICHAZ, FGHAZ, and CGHAZ of weld joints made from two kinds of HSLA steels with 0 or 0.079 wt pct Nb were prepared by means of heat treatment. Optical microscopy and transmission electron microscopy were used to observe microstructures and the distribution of nanosized precipitates in the simulated weld heat-affected zone (HAZ). Mechanical properties of the simulated HAZ were measured by tensile tests, and the corrosion behavior in simulated seawater was studied using electrochemical and immersion tests. It was shown that the ICHAZ and CGHAZ possess the worst overall mechanical properties in both kinds of HSLA steels, and the corrosion resistance in the descending order was the BM, TZ, FGHAZ, ICHAZ, and CGHAZ. Contrasting Nb-bearing and Nb-free steel demonstrated that the strength and corrosion resistance of the simulated HAZ were enhanced by Nb microalloying, which resulted in precipitation, homogeneous microstructures, and other relative sequences. Moreover, the surface of the Nb-bearing steel formed compact corrosion product films with higher resistance to ion migration; thus, the initiation and propagation of pitting holes were effectively inhibited.     

瓦锡兰RT-flex主机校中与安装的技术要领

船舶主机是船舶动力装置中的重要组成部分,主机安装质量和轴系校中的好坏直接关系到动力装置的正常运行和船舶的航行性能。介绍了瓦锡兰RT-flex主机校中与安装工艺,并进一步分析了安装和校中的各项技术要领,可对主机的实船安装和制定瓦锡兰RT-flex主机安装和校中的工艺标准起到指导作用。     

基于仿真的炼油厂罐区操作再调度策略

针对炼油厂操作过程中所存在的大量操作不确定性,提出了一种基于两层仿真系统的再调度方法保证了调度指令的稳定性。在下层模型中引入罐区操作的不确定干扰,并对初始优化方案进行仿真。上层仿真系统采用启发式寻优的方法,当下层干扰发生后得到保证组分和物料双重平衡的安全方案。基于此安全方案,通过固定混合整数线性优化模型中的二元变量并对方案的偏离进行惩罚从而缩小可行域快速得到局部优化解。以某炼厂罐区操作为例,验证了这一再调度策略的有效性。     

微米级交联聚合物微球对核孔膜的封堵作用

采用核孔膜过滤实验,研究了微米级交联聚合物微球的封堵性能。结果表明,矿化度对SMG-μm 微球的封堵效果有很大影响,随着NaCl的质量浓度增大,封堵效果越好;在压力和微球质量浓度相同时,不同核孔膜孔径的过滤时间有很大差异;SMG-μm 微球在较低压力下的封堵效果优于高压力的封堵效果;实验发现,质量浓度对过滤时间的影响比较复杂,没有明显的规律可循。     

Identification of Impurities in Fresh Shrimp Using Improved Majority Scheme-Based Classifier

The efficient removal of impurities from post-harvest raw shrimp is beneficial to improve the quality of shrimp products. Single feature combined with single classifier results in poor classification rate. Moreover, accuracy of combined classifiers remains unsatisfactory, especially when sound shrimp is mixed with various defective shrimp and impurities. In this study, an improved majority rule (IMAJ) classifier combination scheme was proposed to address this problem. The accuracy of IMAJ (91.53 %) was compared with six other kinds of classifier combination schemes proposed by Kittler. The schemes include Sum (89.93 %), Product (65.99 %), Max (89.76 %), Min (80 %), Median (88.18 %), and Majority (89.2 %). Comparison results indicate that the combination classifier based on IMAJ rule is superior.     

氧化物沉淀-减压蒸馏耦合分离FLiNaK熔盐中的NdF_3

利用氧化物沉淀-减压蒸馏耦合法研究FLiNaK熔盐体系中氟化物的蒸发行为及稀土Nd的分离。高温下氧化物CaO与稀土氟化物NdF_3反应形成难溶于熔盐的稀土氧化物,通过减压蒸馏蒸发、收集冷凝FLiNaK熔盐,提高稀土与熔盐的分离度,促进熔盐的回收利用。研究表明,含有NdF_3(w=3%)的FLiNaK熔盐中加入CaO,730°C下反应6 h,n(NdF_3):n(CaO)=1:3时NdF_3的转化率达95%。X射线衍射(X-ray Diffraction,XRD)分析表明生成的Nd_2O_3主要沉淀在熔盐的底部。经730°C高温沉淀、930°C熔盐蒸馏,冷凝盐中稀土Nd的去污因子达9.4′105,而未经沉淀处理Nd的去污因子为3.1′104,表明高温沉淀蒸馏耦合法使稀土NdF_3转化为氧化物Nd_2O_3,显著增大稀土与FLiNaK的分离度,提高收集盐的纯度。