带对流项的渗流型方程的显格式

１．引言　假设有一种不可压流体在一均匀的、各向同性的刚性多孔柱形介质中流动,流动沿着与水平方向成ａ角进行,则可用下述方程描述其中λ＝ｓｉｎα,ｕ表示介质的含湿度．λ＝０,即表示沿水平方向流动,它和λ≠０的情形分别称为无对流项和有对流项的渗流方程．它们可分别写成下面一般的形式：　渗流型方程是退化抛物型方程,由于它可有退化点（使二阶导数项系数为零的点）,它与正规抛物型方程有很大区别．正规抛物型方程有充分光滑的古典解,渗流方程则不然．即使初值充分光滑,也不能保证渗流方程有光滑的解．实际上,渗流方程可有…     

Methode zur Sofortbestimmung von 113Sn im Eluat von 113Sn/113m In-Generatoren

Es wird eine radiometrische Untersuchungsmethode zur Bestimmung der ¹¹³Sn-Kontamination im Eluat von Sn/In-Generatoren vorgeslellt. Dubei wird das ¹¹³Sn über Membranfilter abgetrennt. Die Berechnung der ¹¹³Sn-Konzentration erfolgt aus den in 2 Kanälen gemessenen Impulsraten von ¹¹³Sn und ^113m ln. Die Untersuchung dauert ca. 5 min.     

影响系统主因素综合筛选技术研究

系统影响因素过多不仅会增加系统建模难度,而且会增加系统模型的不确定性和数据收集工作量,因此提出一种影响系统的主因素综合筛选技术.技术将综合灰色关联度、普通相关技术、逐步回归方法、DEMATEL法以及系统动力学等方法的优点和缺点,通过彼此互补和相互融合技术,使得该技术能够有效地筛选出影响系统的主因素.通过在筛选影响船舶柴油机寿命周期费用主因素的应用,和其他方法的比较和分析,验证了本技术的可行性、有效性和先进性.     

Molecular structure and reactivity of titania-supported transition metal oxide catalysts synthesized by equilibrium deposition filtration for the oxidative dehydrogenation of ethane

The molecular structure and catalytic performance of (MoO_x)_n/TiO₂, (WO_x)_n/TiO₂ and (VO_x)_n/TiO₂ catalysts (synthesized by the equilibrium–deposition–filtration/EDF method) for oxidative dehydrogenation (ODH) of ethane were studied by in situ Raman spectroscopy at 430 °C and catalytic measurements in the temperature range of 420–480 °C. The extent of association within the deposited oxometallic phase followed the sequence (VO_x)_n/TiO₂ >> (MoO_x)_n/TiO₂ > (WO_x)_n/TiO₂; a concurrent trend in reduction susceptibility was evidenced by exploiting the relative normalized Raman band intensities while monitoring the response of the vibrational properties of the catalytic samples under reactive (C₂H₆/O₂/He) and reducing (C₂H₆/He) conditions by in situ Raman spectroscopy. The catalyst reactivity tracks the corresponding trend in reduction susceptibility as evidenced by the in situ Raman spectra. Selective reaction pathways are favored at high coverage whilst combustion routes are activated at low coverages due to the involvement of carrier lattice oxygen sites. The observed apparent reaction rates and activation energies are discussed in relation to various structural and reactivity aspects.     

膜富集-可见漫反射光谱法测定池塘水和维生素B_(12)药片中痕量钴

1-(2-吡啶偶氮)-2-萘酚与钴离子生成暗绿色的络合物,反应后将其过滤到膜上,测得膜表面漫反射光谱,据此提出了膜富集-可见漫反射光谱法测定池塘水和维生素B12药片中痕量钴的方法。钴的质量浓度在0.2~3.0μg·L-1和3.0~10.0μg·L-1范围内与其吸光度呈线性关系,检出限(3s/k)为0.093μg·L-1。方法用于池塘水和维生素B12药片的分析,加标回收率在96.7%~105%之间,测定值的相对标准偏差在1.4%~2.9%之间。     

Optimal insider control and semimartingale decompositions under enlargement of filtration

We combine stochastic control methods, white noise analysis, and Hida–Malliavin calculus applied to the Donsker delta functional to obtain explicit representations of semimartingale decompositions under enlargement of filtrations. Some of the expressions are more explicit than previously known. The results are illustrated by examples.     

Fully Reversible pH‐Triggered Network Formation of Amphoteric Polyelectrolyte Hydrogels

Hydrogels are prepared through free radical copolymerization of MAA and DMAEMA employing only non‐covalent interactions. The formation of hydrogels is dependent on pH as well as copolymer composition as a consequence of balance of predominantly attractive and repulsive ionic interactions and hydrogen bonding. The hydrogels are stable between pH 3 and 8 and for MAA to DMAEMA ratios of 62:38 to 68:32. Elastic and loss moduli are characterized as a function of pH. Hydrogels can reform from swollen microgel particles and offer the opportunity of recyclability. In model experiments it is shown that the flow through porous media can be controlled by varying the pH, which offers new possibilities such as controlling the supply of growth factors in tissue engineering scaffolds or as degradable fluid loss control agents for enhanced oil recovery.     

Multifield computational fluid dynamics model of particulate flow in curved circular tubes

Limitations of mass transfer resulting from non-optimized fluid mechanics can severely affect the performance of synthetic membrane filtration systems. To improve membrane efficiency, modern applications of this technology have extensively used curved membrane ducts that take advantage of Dean vortices (i.e., curvature-induced secondary flows) to minimize membrane fouling. This paper is concerned with a complete three-dimensional analysis of single-phase and two-phase particle/liquid flows around a curved membrane tube. The proposed multidimensional model was implemented in an advanced (next-generation) multiphase computational fluid dynamics (CFD) solver, NPHASE. The results of simulations have been validated against experimental data and compared against other findings available in the literature. The consistency and accuracy of the present approach have been demonstrated. The novel aspects of this work include: the demonstration that azimuthal vortices may bifurcate at Dean numbers lower than previously anticipated, the use of vorticity magnitude as a measure of vortex strength, and the explanation of the role that Dean vortices play to mitigate the effect of gravity on particle settling. The overall results have direct relevance to synthetic membrane fouling during filtration of particle suspensions.     

一种改进的快速窄带扫频信号的研制与应用

本文提出一种改进的快速窄带扫频信号，它介于正弦激励信号与宽带激励信号之间，将该信号用于振动模态测试，具有较高的速度和精度。