多程放大器输出焦斑相对于靶的漂移

 对激光光路中光学元件矩阵分别施加“随机微扰”,用光线追踪程序计算光学元件几何参数失调对放大器漂的移影响。并给出漂移量的统计计算结果。     

Surface‐enhanced Raman scattering‐based approach for DNA detection at low concentrations via polyvinyl alcohol‐protected silver grasslike patterns

A simple method is demonstrated to detect DNA at low concentrations on the basis of surface‐enhanced Raman scattering (SERS) via polyvinyl alcohol‐protected silver grasslike patterns (PVA‐Ag GPs) grown on the surface of the common Al substrate. By the SERS measurements of sodium citrate and thymine, the PVA‐Ag GPs are shown to be an excellent SERS substrate with good activity, stability and reproducibility. With the use of the tested molecule of thymine, the enhancement factor of the PVA‐Ag GPs is up to ~1.4 × 10⁸. The PVA‐Ag GPs are also shown to be an excellent SERS substrate with good biocompatibility for DNA detection, and the detection limit is down to ~10⁻⁵ mg/g. Meanwhile, the assignations of the Raman bands and the adsorption behaviors of the DNA molecules are also analyzed. In this work, the geometry optimization and the wavenumber analysis of adenine–Ag and guanine–Ag complexes for the ground states are performed using density functional theory, B3LYP functional and the LanL2DZ basis set. The transition energies and the oscillator strengths of adenine–Ag and guanine–Ag for the lowest six singlet excited states were calculated by using the time‐dependent density functional theory method with the same functional and basis set. The results show that the charge transfer in the adenine–Ag and guanine–Ag complexes should be the chemical factor for the SERS of the DNA molecules. Lastly, this method may be employed in large‐scale preparation of substrates that have been widely applied in the Raman analysis of DNA because the fabrication process is simple and inexpensive. Copyright © 2011 John Wiley & Sons, Ltd.     

Probing single molecules and molecular aggregates: Raman spectroscopic advances

Development of Raman spectroscopy, profiting from surface‐enhanced Raman scattering and tip‐enhanced Raman scattering techniques, has inspired extensive research interest for trace analysis and dynamic measurements up to single‐molecule level. For another, Raman spectroscopy has also been recognized of significance in solving some important issues relating to molecule aggregates in chemistry and biology, owing to the capability of non‐destructive detection and high‐resolution fingerprints by which molecules and their aggregates can be identified. Herein, we summarize the recent progress of Raman spectroscopy in probing single molecules and molecular aggregates and block out a future prospective of Raman spectroscopy applied in cluster science. Copyright © 2015 John Wiley & Sons, Ltd.     

Evolution of the vortex structures and turbulent spots at the late-stage of transitional boundary layers

The nonlinear evolution process of new vortex structures at the late-stage of the transition, including the 3-D spatial structure of barrel-shaped vortex and dark spots structure observed by experiment research, has been confirmed by our computational results. The formation mechanisms of these structures have been explored. It is revealed that the new vortex structures, the ring-like vortex chain and induced disturbance velocities play a dominant role in the generation of turbulent spots.     

结合面静摩擦因数分形模型的建立与仿真

提出一个确定分形维数和分形粗糙度参数(G')的分形函数,并用分形函数逼近结合面的表面粗糙度.根据分形理论和改进后的尺寸分布,推导了静摩擦因数f的解析解.数字仿真结果表明,f随量纲为一的总法向载荷(P')增加而增加.当D较小或较大时,f与(P')之间存在不同的微凸和微凹弧非线性关系,D=1.2时f与(P')的关系基本上是线性的;当D较小时,f随D增加而增加;当D较大时,f随D增加而减小;f随分形粗糙度参数(G')增加而减小,随相关系数K增加而增加,随材料特性(φ)增加而增加.     

Turbulent spots in boundary layers in a free-piston shock-tunnel flow

In this paper, experiments to detect turbulent spots in the transitional boundary layers, formed on a flat plate in a free-piston shock tunnel flow, are reported. Experiments indicate that thin-film heat-transfer gauges are suitable for identifying turbulent-spot activity and can be used to identify parameters such as the convection rate of spots and the intermittency of turbulence.     

Advanced aspects of electromagnetic SERS enhancement factors at a hot spot

In this paper, we discuss some advanced theoretical aspects of electromagnetic enhancement factors (EFs) in surface‐enhanced Raman scattering (SERS). We focus in particular on the influence of surface selection rules (SSRs) on SERS EFs at hot spots, and the determination of SERS depolarization ratios. Both aspects could be viewed as secondary (compared to the overall magnitude of the SERS EF), but are nevertheless observable experimentally and crucial for a fundamental understanding of SERS. They also share the property that they cannot be studied within the commonly used |E | ⁴ approximation to the SERS EFs, and appropriate tools are developed here to make predictions beyond this approximation in the case of a SERS hot spot. In addition, theoretical estimates of different types of (previously defined) EFs are provided, and their origins discussed for the typical example of a SERS substrate dominated by SERS hot spots. Finally, experimental measurements of SERS depolarization ratios are presented to support the theoretical predictions. Copyright © 2008 John Wiley & Sons, Ltd.     

基于遗传算法的公交智能调度与优化——以南岳衡山景区为例

南岳衡山(以下简称南岳)以“外秀于林,内秀于文”驰名中外,作为风景名胜区近几年游客人数不断攀升。本文利用遗传算法对景区内公交线路的调度模型进行求解。首先,根据景区现有的公共交通资源和旅客的出行规律,构建了以旅游公交营运成本、游客等待成本和游客流失成本三方面优化目标的模型;然后,使用线性加权方法实现对旅客与营运公司双方利益兼顾,进一步完善模型;最后,利用Matlab对实地调研数据的车辆调度方案求解。表明该模型改善了南岳景区旅游交通,满足游客的合理需求,提升了旅游公司经营策略,真正成为“寿岳独秀”的知名品牌。     

游客使用景区移动商务的关键影响因素研究

基于景区移动商务的技术属性和商品属性,结合技术接受模型,建立了游客使用景区移动商务影响因素的结构方程模型.通过网络问卷调查法回收数据,对研究假设和概念模型进行了实证检验.结果显示,感知有用性、感知易用性、主观规范是游客使用景区移动商务的关键影响因素,感知易用性和主观规范同时显著正向影响游客对景区移动商务的有用性感知.最后,根据实证结果对景区移动商务的发展和未来研究的方向提出了相应建议.     

The auto-measurement of the gap of LCD glass plates using sub-pixel accuracy estimation

In this paper, the distance between laser spots has been measured using sub-pixel accuracy estimation and the accuracy has been tested in a noise environment. Here, the correlation like method (CLM) is used for the distance measurement between two laser spots and to count the estimation precision effect under noise factor by relevant CLM theorems. From the maximum value of the data series, then the position of the center of laser spot can be derived by interpolation. The estimation precision effect under noise factor and DC offset are tested and analyzed by a computer system. Also, for improving the estimation precision, a Kalman filter, which is often applied for random estimation and control theorem, is adopted. The innovation research combines CLM, and Kalman filter in sub-pixel accuracy estimation is more precise. This method can be used for measuring the gap of LCD glass plates, of optical strain gauge and the characteristics of spectral, quickly and can be automated.