Optical activity measurement by use of a balanced detector optical heterodyne interferometer

What we believe to be a novel amplitude sensitive optical heterodyne polarimeter in which a Zeeman laser is associated with balanced detector detection was set up. The aim was to measure the optical activity of a quartz crystal with a Cornu depolarizer at high accuracy. The features of this novel polarimeter, which include the use of a two-frequency laser that ensures the accuracy of the measurement, are discussed. Furthermore, the detection sensitivity of the optical activity of a quartz crystal was measured as 8.5x10(-10). To our knowledge, this is the highest sensitivity obtained for optical activity measurement of a quartz crystal when the error of the measurement is also analyzed.     

Dissolution of a multicomponent DNAPL pool in an experimental aquifer

This paper presents the results from a well-defined, circular-shaped, multicomponent dense nonaqueous phase liquid (DNAPL) pool dissolution experiment conducted in a three-dimensional, bench scale model aquifer. The multicomponent pool is a mixture of tetrachloroethylene (PCE) and 1,1,2-trichloroethane (1,1,2-TCA); PCE was the major component and 1,1,2-TCA was the minor component. Downgradient plume concentrations were measured at five specific locations over time until the majority of the 1,1,2-TCA was depleted from the DNAPL pool source. The experimental results suggest distinct spatial-temporal plume patterns for minor DNAPL components versus major DNAPL components. The downgradient concentration varied over time for 1,1,2-TCA while a stable plume developed for PCE. A semi-analytical solution for contaminant transport resulting from dissolution of multicomponent nonaqueous phase liquid pools successfully simulated the plume structure and dynamics for both the major and minor DNAPL components.     

Design of a rotational three-dimensional nonimaging device by a compensated two-dimensional design process

A compensation process has been developed to design rotational three-dimensional (3D) nonimaging devices. By compensating the desired light distribution during a two-dimensional (2D) design process for an extended Lambertian source using a compensation coefficient, the meridian plane of a 3D device with good performance can be obtained. This method is suitable in many cases with fast calculation speed. Solutions to two kinds of optical design problems have been proposed, and the limitation of this compensated 2D design method is discussed.     

Catalytic conversion of 1,2-dichlorobenzene over mesoporous V2O5/TiO2 prepared from spray pyrolysis

Mesoporous V2O5/TiO2 particles were prepared by spray pyrolysis and applied to the catalytic oxidation of 1,2-dichlorobenzene (1,2-DCB). Two different precursors (alkoxide and nanoparticles) for the TiO2 support were used to determine the effects on the texture properties and the catalytic activity of the mesoporous V2O5/TiO2 particles. The 5 wt% V2O5/TiO2 particles had the largest surface area (173 m2/g) and 4.7 nm in average pore size. The catalytic activity of the V2O5/TiO2 particles depended strongly on the loading quantity of vanadium, whereas the P25-derived samples showed no significant change in catalytic activity with weight% of vanadium. The surface area of the V2O5/TiO2 particles prepared using the alkoxide precursor was larger than that of the particles prepared using P25 nanoparticles. The P25-derived V2O5/TiO2 particles, however, showed a higher catalytic activity compared with those alkoxide-derived, which is due to the difference in the vanadium quantity exposed to the pore surface. It was confirmed that the 10 wt% V2O5/TiO2 particles prepared by spray pyrolysis had an excellent activity for the oxidation of 1,2-DCB, particularly at temperatures below 300 degrees C.     

Wetting behavior and nanotribological properties of silicon nanopatterns combined with diamond-like carbon and perfluoropolyether films

A large number of silicon (Si) patterns consisting of nanopillars of varying diameter and pitch have been fabricated and further coated with diamond-like carbon (DLC) and perfluoropolyether (Z-DOL) films. The wetting behavior and nano-adhesion/friction of the patterns are investigated experimentally in relation to the nanostructures and the hydrophobicity of the materials. Measurements of water contact angle illustrate that the patterning-enhanced wettability of the Si flat surface, along with two distinct wettings which are in good agreement with the Wenzel and hemi-wicking states, depended on the value of the pitch-over-diameter ratio. In the case of the coated patterns, three wetting states are observed: the Cassie-Baxter, the Wenzel, and a transition from the Cassie-Baxter into the Wenzel, which varies with regard to the hydrophobic properties of the DLC and Z-DOL. In terms of tribological properties, it is demonstrated that a combination of the nanopatterns and the films is effective in reducing adhesive and frictional forces. In addition, the pitch and diameter of the patterns are found to significantly influence their adhesion/friction behaviors.     

A sharpness-dependent filter for recovering sharp features in repaired 3D mesh models

This paper presents a sharpness-based method for hole-filling that can repair a 3D model such that its shape conforms to that of the original model. The method involves two processes: interpolation-based hole-filling, which produces an initial repaired model; and post-processing, which adjusts the shape of the initial repaired model to conform to that of the original model. In the interpolation-based hole-filling process, a surface interpolation algorithm based on the radial basis function creates a smooth implicit surface that fills the hole. Then, a regularized marching tetrahedral algorithm is used to triangulate the implicit surface. Finally a stitching and regulating strategy is applied to the surface patch and its neighboring boundary polygon meshes to produce an initial repaired mesh model, which is a regular mesh model suitable for post-processing. During post-processing, a sharpness dependent filtering algorithm is applied to the initial repaired model. This is an iterative procedure whereby each iteration step adjusts the face normal associated with each meshed polygon to recover the sharp features hidden in the repaired model. The experiment results demonstrate that the method is effective in repairing incomplete 3D mesh models.     

iCluster软件叠前时间偏移模块的优化方法

对中国石化石油勘探开发研究院南京石油物探研究所iCluster地震成像软件系统中叠前时间偏移（PSTM）模块进行了性能剖析和调优。PSTM模块中,进程间通讯很少,理论上可以得到很好的加速比和可扩展性。由于存在大量的读写磁盘操作,导致CPU占用率很低,性能变差,一旦磁盘读写性能得到了很好的解决,性能将会大幅提升。此外,还发展了iCluster PSTM模块的多线程和混合并行方法。SMP集群上,通过多线程和混合并行方法不仅可以增加单节点的数据处理量,而且也很好地缓解了PSTM模块各进程对IO的竞争。另一方面,对原始代码中的热点循环进行了优化,实现了对代码的向量化,在某工区数据的测试中,性能提升了36.3%     

基于UNICORE的地震网格计算应用插件

地震网格计算应用插件以油气地震勘探应用网格（SeisGrid）为运行框架,完成网格环境下的地震成像计算。在iCluster叠前深度偏移成像软件系统运行环境、网格计算需求和并行计算模式分析的基础上,提取适合在客户端完成的应用功能及最迫切需要在网格环境运行的计算功能,借助于SeisGrid客户端的强大网络功能和安全机制,研发了面向网格的地震应用插件。地震网格计算应用插件可方便地使用SeisGrid管理的各计算中心的网格计算资源,实现对分布式计算资源的无缝、安全和简单易行的访问,通过网络访问远程网格计算资源和iCluster应用软件资源,完成网格环境下的叠前深度偏移成像计算。     

深度-射线域偏移速度分析

根据波场外推理论和共角度成像条件,给出了基于深度-射线域共成像道集的偏移速度分析方法。该方法采用速度扫描技术,以共成像点道集同相轴拉平,即成像质量最优为准则提取速度修正量,可以采取沿构造层位或道集深度2种方式进行交互式速度分析。用Marmousi模型对该速度分析方法进行了沿深度方向和沿层位的偏移速度分析测验,结果表明,用该方法提取的速度修正量与预设的偏移速度误差几乎一致。     

６４位集群计算平台波动方程叠前深度偏移的性能优化

详细介绍了iCluster波动方程叠前深度偏移软件系统所采用的集群并行计算策略,以及在６４位集群计算平台上开展的计算性能优化工作和取得的成果。给出了大量软件优化和性能测试结果,包括波动方程叠前深度偏移处理程序运行分析、MPI并行计算运行分析、不同编译器和编译参数测试对比、不同FFT算法效率测试对比、IA32和IA64平台软件运行效率对比测试及并行加速比测试等结果。以原来基于2.6GHZ Xeon系统上的软件运行效率作为基准,在基于1.4GHz Itanium2的系统上,经过优化的波动方程叠前深度偏移程序其计算性能提高了９倍左右。其性能的提高主要归功于３个因素,即６４位处理器硬件性能的提高、优化编译器的贡献和Intel MKL数学库中DFT程序的贡献。试验和分析表明,对于波动方程叠前深度偏移计算,基于千兆以太网的集群计算机系统可以在较大规模配置下,仍然能保持很高的并行加速比。面对数据规模和计算规模的挑战,向６４位计算平台的迁移是未来几年内地球物理计算的必然发展方向。IA64平台上软件计算性能的优化,既有巨大潜力,又有可观的经济价值。