低压配电用SPD动作负载试验研究

依据IEC61643-1:2005中7.6.4的规定,对Ⅰ、Ⅱ级电涌保护器进行动作负载试验中的确定续流大小的预备性试验与动作负载预处理试验时的现象,通过对冲击相角、施加不同Uc值、SPD(SPD,surge protection devices)设计结构等的分析,提出①Ⅰ、Ⅱ级电涌保护器在动作负载试验中最易出现续流或者燃烧爆炸等危险现象的相角为40°～60°和220°～240°,而并不是90°和270°;②试验时施加的Uc值对试验现象起着重要作用,Uc越小试品越不易产生续流等现象,Uc越大越易产生续流等;③内部使用铜织带作为连接结构的SPD,在试验过程中,铜织带或因过长、或因高低压连接点距离太近等结构因素产生高压端铜织带被电动力打断等现象;④通过对相角和不同Uc的分析,提出了一种利用Uc的变化率(K)及K.Usinθ来对确定续流与预处理试验中最易发生续流相角进行解释。这对工程师对理解Ⅰ、Ⅱ级电涌保护器进行动作负载试验时的试验现象提供了试验和理论支持,并为SPD设计者提供了修整思路,具有一定的工程意义。     

不同边界条件下非完整井抽水试验渗透系数计算方法研究

在实践中经常会遇到比较复杂的水文地质条件,或者裘布衣假定不成立,或者计算太过复杂,现有的规范、手册等未给出这些条件下稳定流抽水试验渗透系数的求解公式。为此,本文运用汇源理论和镜像法,结合具体工程实践,推导了在无限厚含水层和不同边界条件下非完整井稳定流抽水试验渗透系数的计算公式,通过工程勘察实践验算,验证了计算方法和公式的合理性。     

Phyto-Niosomes: In Vitro Assessment of the Novel Nanovesicles Containing Marigold Extract

Herbal compounds, so-called phytoconstituents, illustrate poor absorption by living cells. Phytosomes are advanced form of herbal compounds that show higher absorption rate and bioavailability, which results better than conventional plant extracts. Niosomes, which are made of nonionic surfactants, create better chemical and stability conditions besides lipid vesicles. This study covers the preparation, characterization and cell culture applications of phyto-niosomes of Marigold extract. Before the encapsulation process, extracts of selected plants were prepared and the extract that presents best bioactivity was chosen. The resulting phyto-niosomes were characterized and their biological activities including cytotoxicity, wound healing and antioxidant activity were investigated.     

Statistical tests for a single change in mean against long‐range dependence

Statistical tests are introduced for distinguishing between short‐range dependent time series with a single change in mean, and long‐range dependent time series, with the former making the null hypothesis. The tests are based on estimation of the self‐similarity parameter after removing the change in mean from the series. The focus is on the GPH (Geweke and Porter‐Hudak, 1983) and local Whittle estimation methods in the spectral domain. Theoretical properties of the resulting estimators are established when testing for a single change in mean, and small sample properties of the tests are examined in simulations. The introduced tests improve on the BHKS ( Berkes et al., 2006 ) test which is the only other available test for the considered problem. It is argued that the BHKS test has a low power against long‐range dependence alternatives and that this happens because the BHKS test statistic involves estimation of the long‐run variance. The BHKS test could be improved readily by considering its R/S‐like regression version which estimates the self‐similarity parameter and which does not involve the long‐run variance. Yet better alternatives are to use more powerful estimation methods (such as GPH or local Whittle) and lead to the tests introduced here.     

新疆油田呼图壁储气库气井管柱腐蚀实验研究

新疆油田公司依据中石油股份公司储气库建设要求,启动了＂呼图壁气田改建储气库＂建设工作。储气库的主要气源是从土库曼斯坦进关的天然气,该天然气中CO2≤2%,CO2分压最大为0.68MPa,采出时在井口及井底,天然气的含水量普遍高于对应温度、压力下的天然气饱和含水汽量,即低于露点温度,会导致较为严重的CO2腐蚀。通过分析知道呼图壁气田影响二氧化碳腐蚀的环境影响因素主要有二氧化碳分压、地层水矿化度及Cl-含量、温度、流速等,由此设计了室内模拟实验条件;评价了P110、3Cr110、普通13Cr110、HP1-13Cr110抗CO2（含Cl-）腐蚀性能。得到了室内模拟条件下,不同目标管材的平均腐蚀速率与局部腐蚀速率,根据实验结果确定不同管材的腐蚀状况,为储气库气井管柱的选材提供依据。     

棉花长度试验方法 手扯尺量法不确定度的评价方法

介绍了测量不确定度评估的一般方法和步骤,通过棉花手扯长度测量不确定度的评定应用实例阐述了测量不确定度的评定方法。     

基于CURE算法的电子装备时变误差分析

针对当前靶场试验中现有试验数据误差处理方法的不足,对电子装备试验过程中存在的时变误差进行了分析,提出了时变稳定度、时变一致性和精度—时间概率3项考核电子装备时变误差的指标。采用一种基于CURE算法的电子装备时变误差分析处理方法,对两型激光测距设备的误差精度进行了对比分析。试验结果表明对于某些存在时变误差的电子装备,上述算法具有良好的区分度,证明了该方法的有效性。     

Revisiting the methods of determining hydraulic conductivity of saturated expansive clays in low-compressibility zone

The hydraulic conductivity of saturated clays is commonly determined either directly by monitoring water flux or indirectly based on Terzaghi's consolidation equation. Similar results are generally obtained from the two methods, but sometimes a significant difference can be observed, in particular for expansive soils. In this study, the hydraulic conductivities determined by the two methods are first compared based on existing data in the literature. The indirect method is then revisited attempting to explain the difference identified. A modified effective stress, considering physico-chemical interaction between face-to-face oriented particles, is finally introduced to better describe the compressibility of expansive clays and to further improve the indirect method in determining hydraulic conductivity of such soils in the low-compressibility zone. Extra tests were performed on Gaomiaozi (GMZ) bentonite slurry and the results obtained allowed the modified indirect method to be verified.     

Assessment of cleaning effectiveness for new ecological systems on ancient tempera icon by complementary microscopy techniques

The study presents an old icon painted in egg tempera on lime wood, with a poor conservation condition and clogged dirt deposits. The icon is attributed to an anonymous painter of XIXth century and to the neo‐classical style of painting. The painting layer was done with only a hand full of pigments, earth colors that were often used in painting the icons from XVIIth to XIXth century in Eastern Europe, that have Byzantine influences. Taking into consideration the nature and the structure of the materials from the upper layers of the painting, affected by deposits of dirt over time, a series of cleaning recipes were studied, using the so called cleaning tests with compatible mixtures of different juices and infusion from indigenes plants, that were freshly done and odorless. A low alkaline 95% ethyl alcohol solution, combined with a few drops of ammoniac 25%, was used as a reference system, due to its compatibility with the greasy deposits found on the polychrome layer and on the wood. The cleaning capacity of the new systems used, in comparison with the standard solution, was analyzed through modern analytical methods of evaluating the degree of cleaning, more exactly by means of visible and UV reflectography, CIE L*a*b* colorimetry by reflection assisted by SEM‐EDX and IR spectroscopy. Microsc. Res. Tech. 77:1060–1070, 2014. © 2014 Wiley Periodicals, Inc.