Vertical Bearing Capacity of a Partially-Embedded Pipeline on Tresca Soils

Slip-line field solutions are presented for the ultimate load of submarine pipelines on a purely cohesive soil obeying Tresca yield criterion, taking into account of pipe embedment and pipe-soil contact friction. The derived bearing capacity factors for a smooth pipeline degenerate into those for the traditional strip-line footing when the embedment approaches zero. Parametric studies demonstrate that the bearing capacity factors for pipeline foundations are significantly influenced by the pipeline embedment and the pipe-soil frictional coefficient. With the increase of pipeline embedment, the bearing capacity factor Nc decreases gradually, and finally reaches the minimum value (4.0) when the embedment equals to pipeline radius. As such, if the pipeline is directly treated as a traditional strip footing, the bearing capacity factor Nc would be over evaluated. The ultimate bearing loads increase with increasing pipeline embedment and pipe-soil frictional coefficient.

Beam splitter entangler for light fields

We propose an experimentally feasible scheme to generate various types of entangled states of light fields by using beam splitters and single-photon detectors. Two beams of light fields are incident on two beam splitters respectively with each beam being asymmetrically split into two parts in which one part is supposed to be so weak that it contains at most one photon. We let the two weak output modes interfere at a third beam splitter. A conditional joint measurement on both weak output modes may result in an entanglement between the other two output modes. The conditions for the maximal entanglement are discussed based on the concurrence. Several specific examples are also examined.

Entanglement purification based on photonic polarization parity measurements

We present an entanglement purification protocol for photonic mixed entangled states based on the two-mode polarization nondemolition parity detectors. Without the use of the controlled-NOT (CNOT) operations, the efficiency of our protocol can nearly approach that of the CNOT protocol. The total successful probability of our protocol can be nearly enhanced to the quantity twice as large as that of the linear-optics-based protocol. Besides, our protocol adopts common photon detectors rather than the sophisticated single-photon detectors required in the linear-optics-based protocol.

Universal Greenberger-Horne-Zeilinger-state analyzer based on two-photon polarization parity detection

We present a universal analyzer for the three-particle Greenberger-Horne-Zeilinger (GHZ) states with quantum nondemolition parity detectors and linear-optics elements. In our scheme, all of the three-photon GHZ states can be discriminated with nearly unity probability in the regime of weak nonlinearity feasible at the present state of the art experimentally. We also show that our scheme can be easily extended to the analysis of the multi-particle GHZ states.

一种基于PSD器件的改进型角度测量方法

提出一种基于平行平板干涉仪的改进型角度测量方法。为了实现较大的偏转角度测量，该平行平板干涉仪引入了一位置探测系统。平面反射镜的引入提高了角度测量的分辨率。实验验证了可在近3度的范围内实现被测偏转角度的高精度测量。并且作为一位相调制型干涉仪，其小角位移测量实验的重复精度可达5.5×10^(-8)rad。

四区域法消除偏振棱镜缺陷对波片相位延迟测量的影响

在起偏器待测波片检偏器系统基础上提出一种四区域测量波片相位延迟量的方法。调整待测波片和检偏器的方位角,获得相应的四组光强值,通过线性运算得到待测波片的相位延迟量,完全消除了起偏器和检偏器不完全消光带来的误差。由于测量系统中不存在标准波片或其他相位调制元件,允许测量波长仅受偏振棱镜和探测器的限制,因此四区域法可适用于很大波长范围内的波片测量。以λ/4波片为例,理论分析了测量系统利用四区域测量法后的仪器误差为σ≤±3.49065×10-3rad(约0.2°),精度比原算法提高约1个数量级。实验验证了四区域法能有效提高系统精度。

基于电光调制的激光光谱整形技术

提出了一种新型的基于电光调制的激光光谱整形方案，该整形技术可以减轻啁啾脉冲放大系统中的增益窄化效应。傅立叶变换限的宽带种子激光脉冲通过光学展宽器线性展宽后，耦合到加载有整形电脉冲的集成波导调制器中进行整形，整形电脉冲由孔径耦合带状线电脉冲发生器产生。由于线性啁啾脉冲时间-频率的直接对应关系，在时域内对宽带种子激光脉冲整形，其光谱也得到了同样形状的整形。模拟了整形光谱形状，相应的整形电脉冲波形，分析了该整形技术的光谱整形分辨率，以及整形过程中引入的相位畸变。

两根掺镱大芯双包层光纤激光器获得113W同相输出功率

利用一个自成像共焦腔和一个空间滤波器实现了两掺Yb大芯光纤激光器的位相锁定。观测到稳定的具有高对比度的干涉条纹。相干条纹的对比度为59%，而非相干时对比度为6%。中心条纹的宽度与理论计算结果吻合得很好。对同相模式而言，位相锁定激光器阵列输出达到113W，对应的斜率效率为38.5%。

基于上转换发光技术的生物传感器及其应用

为实现对特定生物分子的高灵敏度快速检测与分析。采用上转换发光材料作为标记物，研制成功一台基于上转换发光技术的新型光学免疫生物传感器。该传感器利用上转换发光材料在红外光激发下发射可见磷光的特性，通过对免疫层析试纸条上经生物反应而结合上去的上转换发光材料颗粒的含量进行检测，计算出被测样品中特定生物分子的浓度。实验结果表明，该传感器具有较好的生物特异性，对兔抗鼠疫免疫球蛋白(IgG)标准样品的检测灵敏度达到ng／ml量级，并在200～6000ng／ml浓度范围内具有良好的线性响应特性，相关系数R^2≥0．95；

上转换发光免疫试纸条扫描检测系统研究

研制了一种以上转换发光材料作为标记物的扫描检测系统，有别于传统的测量方法，可做出定量和多重分析．扫描检测系统以扫描方式逐点测量经生物反应而结合上去的UCP颗粒的含量，记录整个免疫试纸条的信息，计算出被测样品中特定生物分子的浓度．实验结果表明，该系统对兔抗鼠疫免疫球蛋白（IgG）标准样品的检测灵敏度达到百ng／mL量级，且具有变异系数小于6％的重复性，符合生物免疫测定的要求．

基于一维CCD的免疫层析试纸条检测系统

本文报道的基于一维CCD的免疫层析试纸条检测系统是一种以上转换磷光材料（UCP）作为标记物的生物传感器。该系统通过检测生物反应后试纸条上UCP颗粒的含量，计算出被测样品中特定生物分子的浓度，可以实现对多种病原体的快速定性与定量检测。本检测系统对0—60ns／ml系列标准样品的检测结果具有很好的线性响应特性，且与扫描型检测系统的检测结果十分接近。

显微成像荧光屏用无机闪烁单晶薄膜的研究进展

随着第三代同步辐射源的出现，由荧光屏和CCD耦合组成的、具有亚微米级空间分辨率、快速在线成像功能的探测器在医疗、安检、工业、科研等领域将会得到广泛应用．本文主要综述了成像荧光屏用材料的概况和发展趋势，重点阐述了闪烁单晶薄膜的研究及发展情况．

High-performance 4H-SiC based metal-semiconductor-metal ultraviolet photodetectors with Al2O3 SiO2 films

4H-silicon carbide (SiC) metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors with Al2O3/SiO2 (A/S) films employed as antireflection/passivation layers have been demonstrated. The devices showed a peak responsivity of 0.12 A/W at 290 nm and maximum external quantum efficiency of 50% at 280 nm under 20 V electrical bias, which were much larger than conventional MSM detectors. The redshift of peak responsivity and response restriction effect were found and analyzed. The A/S/4H-SiC MSM photodetectors were also shown to possess outstanding features including high UV to visible rejection ratio, large photocurrent, etc. These results demonstrate A/S/4H-SiC photodetectors as a promising candidate for OEIC applications. (C) 2008 American Institute of Physics.

A novel proline rich bombesin-related peptide (PR-bombesin) from toad Bombina maxima

A novel bombesin-related peptide was isolated from skin secretions of Chinese red belly toad Bombina maxima. Its primary structure was established as pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH2. The amino-terminal (N-terminal) 8-residue segment comprising four prolines and three basic residues is extensively different from bombesins from other Bombina species. The peptide was thus named proline rich bombesin (PR-bombesin). PR-bumbesin was found to elicit concentration-dependent contractile effects in the rat stomach strip, with both increased potency and intrinsic activity as compared with those of [Leu(13)]bombesin. Analysis of different bombesin cDNA structures revealed that an 8 to 14- nucleotide fragment replacement in the peptide coding region (TGGGGAAT in the cDNAs of multiple bombesin forms from Bombina orientalis and CACCCCGGCCACCC in the cDNA of PR-bombesin) resulted in an unusual Pro-Pro-Arg-Pro-Pro motif in the N-terminal part of PR-bombesin. (C) 2002 Elsevier Science Inc. All rights reserved.