金沙江乌东德水电站坝址高边坡稳定性研究

高边坡是中国西部水电工程建设常见工程问题之一。金沙江乌东德水电站坝址两岸自然边坡高达830~1036 m,其稳定状况直接事关工程安全。以大量地质调查资料为基础,将地质宏观分析与数值分析计算相结合,研究坝址高边坡稳定性,预测工程边坡可能失稳模式,为治理工程设计提供重要依据,可作为类似工程参考。     

基于多源降水数据估算澜湄流域可能最大降水

基于多源降水数据估算流域可能最大降水（PMP），对推求稀缺资料地区的设计和校核洪水具有重要意义。选取澜沧江-湄公河流域为研究区域，以APHRODITE降水数据集和实测降水为基准，评价CHIRPS、MSWEP和PERSIANN三套全球降水产品的精度，基于改进的统计法估算1天和3天的PMP。结果表明：（1）MSWEP产品具有较高的精度和降水探测能力；（2）栅格尺度下MSWEP与APHRODITE降水数据的PMP估算结果显著相关；（3）基于MSWEP卫星降水数据估算的湄公河流域1天和3天的PMP分别为122 mm和192 mm，与其他的PMP估算结果相近。卫星降水数据可为缺乏资料地区的PMP估算提供重要参考依据。     

费托合成钴催化剂的失活与再生研究进展

为降低费托合成钴催化剂成本,提高费托合成钴催化剂的稳定性和寿命,分析了费托合成钴催化剂的失活与再生机理,论述了费托合成钴催化剂的再生方法。结果表明,中毒、烧结长大、积碳、氧化及固相反应是造成费托合成钴催化剂失活的主要原因。通过净化原料气、调节钴与载体相互作用、调整催化剂配方及工艺条件、控制钴颗粒尺寸及体系中水和H2的分压比等措施可以提高催化剂稳定性和寿命。通过脱蜡、氧化、还原可实现催化剂再生,氧化是再生的关键步骤,要注意氧化过程中升温速率、热量移除等问题;多次的氧化和还原过程可增加再生催化剂中金属钴与还原助剂的均匀性,提高再生催化剂的活性。     

聚酚氧树脂/酚醛树脂混合物用于制备覆膜砂的研究

聚酚氧树脂具备高韧性高软化点的特点,其与热塑性酚醛树脂共混可以显著提高酚醛树脂的韧性,提高常温强度和热强度,并改善覆膜砂溃散性。将聚酚氧树脂与酚醛树脂共混制备覆膜砂,实验结果表明,聚苯氧树脂添加10%时,覆膜砂拉伸强度提高15.2%,弯曲强度提高12.8%,熔点提高3℃,溃散率提高提高20%,在铝合金铸件上面具有较好的应用前景。     

β-SiC微粉的气流分级工艺

采用生产型流化床对喷式气流粉碎分级机对β-SiC微粉进行气流粉碎分级实验研究,通过探讨不同的工艺参数对分级效果的影响,确定最佳进料速率、每一个粒级的产物所对应的最佳分级轮转速和进料粒度,并优化工艺流程.结果表明,最佳进料速率为42 kg/h;针对不同粒度的产物确定了最佳的分级轮转速;采用优化工艺能够高效地、稳定地获得不同粒径的分级产品,可实现粒度大于W2.5产品的β-SiC微粉的精细分级,分级产物粒度分布窄,颗粒形貌均匀.     

基于80C196KC ＆ PSD4235G2在线编程的实现

可编程外围器件PSD应用于MCU系统后，单片机可以执行一个存储器的代码，同时擦除和编程另一个存储器，因而可以通过上位机远程更新用户软件，实现在线编程(In Application Programming)。同时，简化了MCU外围电路的设计，增加了系统的可靠性和稳定性。     

二维阀先导级污染颗粒分布的数值模拟

二维阀将先导级和功率级集成在一个阀芯上，易于实现阀的快速工作和高频响应，具有体积小、性能稳定、功重比大等优点。通过数值计算，分析不同参数条件下固体颗粒在二维阀内的分布特点和规律，揭示二维阀对油液污染的敏感程度。结果发现：阀芯转动形成的节流口，其上下游压差与射流形成的旋涡离心力的共同作用，使得固体颗粒物极易进入阀套斜槽区形成聚集现象；固体颗粒在旋涡中心区域分布较少，在旋涡边缘区域，特别是阀套斜槽外侧浓度较高。节流口开度、固相密度、颗粒粒径的不同，均对固体颗粒的分布产生影响，总体来看，旋涡态流束对其分布影响最大，即斜槽周边浓度大、中间区域浓度低，二维阀对油液污染较为不敏感。阀芯正、反转对阀套斜槽区内固相颗粒的体积分数分布影响不大。     

A strategy for highly dispersed Mo<Subscript>2</Subscript>C/MoN hybrid nitrogen-doped graphene via ion-exchange resin synthesis for efficient electrocatalytic hydrogen reduction

Molybdenum carbide/molybdenum nitride hybrid N-doped graphene (abbreviated as Mo₂C/MoN/NG), as an efficient electrocatalyst for the hydrogen evolution reaction (HER), was synthesized via simple ion-exchange resin synthesis followed by a two-step annealing process, which increased the dispersion degree of the electrocatalyst’s active sites on the support skeleton and simplified the synthetic conditions. Additionally, N-doped graphene (NG) enhanced the electron transfer and reduced the inner resistance. The material has a graphene-like morphology and highly dispersed Mo2C/MoN nanoparticles about 2 nm in diameter on the NG. X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy revealed that Mo₂C/MoN/NG consisted of Mo₂C and MoN composited together. Finally, Mo₂C/MoN/NG exhibited remarkable performance as an electrocatalyst for the HER with a small overpotential of 78.82 mV and a small Tafel slope of 39.3 mV·dec^?1 in a 0.5 mol·L^?1 H₂SO₄ solution. Its activity was approximately 30% lower than that of 20% Pt/C and 60% higher than that of NG. Also, it exhibited a low onset overpotential of 24.82 mV, which is similar to the theoretical HER potential. Our work provides a foundation for advanced HER applications of molybdenum compounds.

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感应电机两种非线性观测器的比较研究

基于感应电机在静止坐标系下的非线性模型,采用模型参考自适应控制理论和扩展卡尔曼滤波算法,设计了两种非线性观测器,对转子电阻和转子磁链进行了观测.通过仿真证明了所设计的观测器的正确性,并对两种观测器的性能进行了分析比较.     

Flood Frequency Analysis of Interconnected Rivers by Copulas

Flood frequency analysis (FFA) considering the confluence of interconnected rivers is important for hydraulic structures (such as dams or diversions) design, but it has received little attention. This study develops a copula-based method for FFA and quantile estimation considering the confluence of two interconnected rivers, along with the uncertainty estimation by a nonparametric bootstrapping algorithm. Flood probability distribution and return periods are estimated for the two rivers by mapping from bivariate to univariate peak flow quantile estimation. The methodology is applied to the case study of Qezel Ozan and Shahrud Rivers which merge to one of the largest reservoir dams in Iran: Sefidrud (Manjil) dam. According to the results from Peak flow records from Gilvan station (GPF) at Qezel Ozan River and from Loshan station (LCF) at Shahrud River, Gaussian copula with Weibull and gamma margins fits best. Also, it shows that some peak flow quantiles with the same magnitudes have a different probability of occurrences at the confluence of the rivers, and the bivariate estimation uncertainty usually plays an important role in FFA. These findings suggest the use of bivariate instead of univariate distributions to the peak flows at the confluence of interconnected rivers, in which the sampling uncertainty should be considered.