气—液鼓泡塔中流动域和气含率的分布

利用压力传感器测定了气、液两相鼓泡塔内不同轴、径向位置上压强的脉动信号,分析了压强的脉动特征,计算了各种操作条件下塔内不同轴向位置截面上的平均气含率,发现在不同操作条件下,塔内可能出现不同的流动域分布,即全塔均匀鼓泡域、全塔过渡域、全塔湍动鼓泡域以及均匀鼓泡域,过渡域和湍动鼓泡域中的相邻2种或3种流域同时出现在塔内不同高度上。提出了不同轴向位置流域转变的判据。并发现,同一截面的不同径向位置基本处于同一流域内。同时研究了鼓泡塔内气含率在轴向上的分布规律,给出了不同流动域内气含率的关系式。     

土体固结粉在软土地基加固中的应用研究

针对上海地区软土地基特点,利用工业废渣为主要原料配制成新型土体固结材料——土体固结粉。通过室内的无侧限抗压强度及XRD试验得出其固化土的强度性能及加固机理;再通过室外原位搅拌桩施工及芯样试验进行分析,研究了土体固结粉在软土地基加固实际工程中的适用性。     

Estimation bias of ocean current measured by along-track interferometric synthetic aperture radar and its compensation methods

In previous works on current measured by along-track interferometric synthetic aperture radar (ATISAR), the decorrelation function of an ocean-surface backscattering signal was usually assumed to be a real Gaussian function, i.e. the phase term was omitted. In this study, it is proved that the omission of the phase term included in the decorrelation function results in a significant estimation bias that can be modelled by a higher-order function of time lag and that the coefficients of this higher-order function can be expressed as a series of higher-order Doppler spectral moments. This model is validated by the scatterometer data obtained from an experimental wind-wave tank. The estimation bias especially needs to be considered for the ATISAR system with a long time lag. Simulation results show that if the time lag is equal to the coherence time, the estimation bias of the current can reach about 0.2 m s^?1, which is not insignificant in high-precision current-retrieving applications. However, because most real-life ATISAR systems, including TerraSAR-X, operate with time lags significantly shorter than the expected coherence time, the estimation biases in these systems are relatively small or even negligible. Finally, four possible compensation methods for the estimation bias are proposed and discussed.     

Recent climate variability and its impact on precipitation,temperature, and vegetation dynamics in the Lancang River headwater area of China

The alpine ecosystem is one of the most fragile ecosystems threatened by global climate change. The impact of climate variability on the vegetation dynamics of alpine ecosystems has become important in global change studies. In this study, spatially explicit gridded data, including the Moderate Resolution Imaging Spectroradiometer (MODIS) land-surface temperature (LST) product (MOD11A1/A2), the Tropical Rainfall Measuring Mission (TRMM) rainfall product (3B43), and MODIS net primary productivity (NPP) product (MOD17A3), together with meteorological observation data, were used to explore the spatio-temporal pattern of climate variability and its impact on vegetation dynamics from 2000 to 2012 in the Lancang River headwater area. We found that the variation patterns of LST, precipitation, and NPP in the study area showed remarkable spatial differences. From the northwest to the southeast the spatial variation of average annual LST exhibited a decreasing–increasing–decreasing–increasing pattern. At the same time, most of the study area exhibited an increasing LST during the growing season. The annual precipitation increased in the semi-arid northern part, whereas it decreased in the semi-humid southern part. The precipitation variability during the growing season has a pattern similar to the annual precipitation variability. Although the majority of the regions have seen an NPP increase from 2000 to 2012, the responses of the vegetation to the varied climate factors were spatially heterogeneous. The alpine–subalpine meadows in the high-altitude areas were more sensitive to climate variability in the growing season. It is argued that satellite remote-sensing products have great potential in investigating the impact of climate variability on vegetation dynamics at the finer scale, especially for the Lancang River headwater area with complex surface heterogeneity.     

EFFECT OF SURFACE ROUGHNESS ON THE ADHESION OF ELECTROLESSLY PLATED PLATINUM TO POLY(ETHYLENE TEREPHTHALATE) FILMS

Poly(ethylene terephthalate) films were treated with aqueous sodium hydroxide solutions of different concentrations for various times. The rate of weight loss increased with the addition of a swelling agent (methylene chloride) or a cationic surfactant. The surface roughness of the treated films was determined from atomic force microscopy (AFM) and pore diameter was obtained from scanning electron microscopy (SEM). In general, surface roughness was found to increase with increasing weight loss for the treated films. A maximum roughness was obtained for samples with a weight loss of approximately 15-20%, beyond which the roughness of the samples decreased. The addition of methylene chloride and surfactant resulted in an almost two-fold increase in the roughness for all treatment times investigated. The adhesion of electrolessly plated platinum film was dependent on the contact area produced by chemical treatment. Treatments producing smaller diameter pores of greater depth gave better adhesion.     

Enantiomer-based specificity in pheromone communication by two sympatricGnathoirichus species (Coleoptera: Scolytidae)

The aggregation pheromone ofGnathotrichus retusus was isolated and identified as (S)-(+)-sulcatol (6-methyl-5-hepten-2-ol). In laboratory and field experiments,G. retusus responded to (S)-(+)-sulcatol, but not to (±)-sulcatol, which was attractive to the sympatric species,G. sulcatus. G. sulcatus did not respond to optically pure (S)-(+)-sulcatol, but began to respond when 1% (R)-(–)-sulcatol was present in an enantiomeric mixture.Research supported by the National Science Foundation, U.S.A. (Grant BMS-74-13643), and the Natural Sciences and Engineering Research Council of Canada (Co-op grant A0243 and Operating Grant A3881 and A3785).     

基于云计算的 Excel 数据处理效率优化研究*

为了提高Excel软件的数据处理效率,需建立一个能满足高精确度、高效率、易使用的计算环境。论文建立圆柱螺线优化插值模型,在Excel中通过五组测斜数据计算井眼曲率,再根据云计算可弹性增加计算节点的特点,将Sympho‐ny DE并行软件搭建在本地私有云环境下,通过增加计算节点数目对比运算效率与计算精度。结果表明：随着计算节点数的增加,运算效率大大提高,计算结果更加精确。     

Characteristics of polyvinylpyrrolidone-layered silicate nanocomposites prepared by attrition ball milling

Polyvinylpyrrolidone (PVP)/sodium montmorillonite (MMT) nanocomposites prepared via the solution intercalation method were investigated by UV/vis, SEM, X-ray diffraction, TEM, FT-IR and PLM (polarized light microscopy). PVP/MMT nanocomposites show exfoliation below 20 wt% MMT and intercalation above this concentration. Nanocomposites retain good optical clarity and increased thermal resistance with MMT content. The compatibility between PVP and MMT and their enhanced properties may be explained by hydrogen bonding interactions. In addition, the nanocomposites prepared under more rigorous mixing conditions show better transparency because the smaller particle sizes are induced. In addition, the study on optically clear PVP/MMT suspensions helps one to understand how optical anisotropy of MMT is affected by the existence of polymer in aqueous solution.     

Synthesis and physicochemical characterization of amphiphilic block copolymer self‐aggregates formed by poly(ethylene glycol)‐block‐poly(ϵ‐caprolactone)

Diblock copolymers with different poly(ε‐caprolactone) (PCL) block lengths were synthesized by ring‐opening polymerization of ε‐caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG‐OH, MW 2000) as initiator. The self‐aggregation behaviors and microscopic characteristics of the diblock copolymer self‐aggregates, prepared by the diafiltration method, were investigated by using ¹H NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG–PCL block copolymers formed the self‐aggregate in an aqueous environment by intra‐ and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations of the block copolymer self‐aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The partition equilibrium constants (K_v) of pyrene, measured by fluorescence spectroscopy, revealed that the inner core hydrophobicity of the nanoparticles increased with increasing PCL chain length. The aggregation number of PCL chain per one hydrophobic microdomain, investigated by the fluorescence quenching method using cetylpyridinium chloride as a quencher, revealed that 4–20 block copolymer chains were needed to form a hydrophobic microdomain, depending on PCL block length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3520–3527, 2006     

均三甲苯氧化合成间二甲基苯甲酸的宏观动力学

研究了由均三甲苯液相富氧催化氧化制备间二甲基苯甲酸的动力学规律 ,考察了反应时间、温度、通气量和氧浓度等因素对均三甲苯和间二甲基苯甲酸浓度的影响 ,根据双膜理论建立了该反应的宏观动力学模型 ,并由实验数据拟合出模型参数 ,经检验模型计算值能较好地与实验数据相吻合