植物油脂/油脚在油田深部堵水调剖中的应用

堵水调剖剂对改善高含水油田的注水开发效果、提高采收率发挥着至关重要的作用。综述了弱凝胶和颗粒类油田传统堵水调剖剂的优缺点和应用现状,介绍了植物油脂的特点及其在新兴领域如植物油聚硫橡胶、植物基生态润滑材料的研究进展、应用推广及存在的问题,提出通过硫化交联、交内酯化和皂化水解等化学改性方法将植物油脂及其工业副产物油脚用于油田堵水调剖领域。植物油脂和油脚价格低廉,化学改性方法简便易操作,对岩心的封堵效果好,在油田深部堵水调剖领域中的应用前景良好。     

Stability evaluation of a power network in connection with a unit regulating exciter based on system frequency characteristics

This paper presents a mathematical model (algorithm) suitable for calculating the transfer function of a practical power network. For this network the steady-slate stability limits are derived and the non-linear characteristics of the transfer function are considered. The computational results obtained by using the proposed model differ from the corresponding ones obtained previously by approximate methods, whereas they are in close agreement with similar results obtained from experimental measurements. The oscillation coefficients of first- and second-order derivatives of the generator current highly characterize the performance of the locus diagram of the generator transfer function. The proposed accurate technique is applied to a part of the Egyptian power system consisting of a power station, a substation and a 500 kV double circuit transmission line.     

The effect of adding sour cherry pulp into yoghurt on the physicochemical properties,phenolic content and antioxidant activity during storage

This study investigated the effect of adding sour cherry pulp into yoghurt on its physicochemical properties, phenolic content, antioxidant activity and sensory characteristics. Sour cherry pulp was added at 0%, 8%, 12% and 16% into the yoghurt, and measures were checked through 14 days cold storage. The increasing sour cherry pulp concentration in yoghurt resulted in increasing pH and whey separation, whereas the values of the other parameters, total solid, fat, protein, ash, titratable acidity and viscosity decreased. During storage, total phenolic contents and antioxidant activity in yoghurts ranged from 20 to 81 μg gallic acid equivalent per mg of sample and from 48% to 86%, respectively.     

8-HQCdCl2H2O as an organic Q-switcher in erbium laser cavity

This paper demonstrated a Q-switched erbium-doped fiber laser (EDFL) using an organic saturable absorber (SA) based on 8-HQCdCl2H2O material. The organic thin film was prepared using the casting process. The proposed Q-switched EDFL has a maximum repetition rate of 143 kHz, minimum pulse duration of 1.85 µs and the highest pulse energy of 167 nJ. The Q-switched peak laser was at a central wavelength of 1 531 nm with a 3 dB bandwidth of 3.52 nm and power intensity of 2.64 dBm.     

Associative Growth of Lactic Acid Bacteria in Cabbage Juice

Combinations of Leuconostoc mesenteroides, Lactobacillus brevis, Pediococcus cerevisiae, and Lactobacillus plantarum were grown in sterile cabbage juice broth. The effects of culture interactions were determined by lag times, generation times, pH change, and total acidity measurements. Fresh filter-sterilized cabbage juice was a better medium than autoclaved cabbage juice, or refrigerated filter-sterilized cabbage juice. The addition of NaCl (2.25%) had a minimal effect on the cultures, except for L. mesenteroides, which was inhibited. In paired association studies, L. mesenteroides was inhibited by all the other cultures, conversely, L. plantarum and L. brevis benefited from most of the culture interactions.     

硼-铝强化板的非线性屈曲有限元分析(英文)

通过有限元方法(FEA)分析强化复合板的非线性屈曲行为。该模型中硼-铝复合材料由硼基体和嵌入其中的不同形态的Al纤维组成。对片层结构的B-Al矩形板施加横向压缩应力,发现强化纤维对具有不同几何形状板材的屈曲行为有明显影响。建模中采用单向、具有矩形截面的强化纤维。结果表明:加载过程中存在一重要的载荷范围,临界屈曲模式在稳态和非稳态之间反复转变。确定由不同的纤维形态和板材高宽比组成的分叉失稳区域。通过ANSYS有限元计算,研究简支边界条件下强化板材的失稳模式,分别得到压应力(σx)与平面收缩(u)以及压应力(σx)与面外挠度(δ)的关系曲线。通过非线性分析,在C1、C2、C3和C4四种形态的纤维中,嵌入C2纤维的板材获得最安全的临界屈服应力。结果表明,FEA非线性屈曲分析可以得到精确的结果。