ERROR ESTIMATION FOR NUMERICAL METHODS USING THE ULTRA WEAK VARIATIONAL FORMULATION IN MODEL OF NEAR FIELD SCATTERING PROBLEM

In this paper, we investigate the use of ultra weak variational formulation to solve a wave scattering problem in near field optics. In order to capture the sub-scale features of waves, we utilize evanescent wave functions together with plane wave functions to approximate the local properties of the field. We analyze the global convergence and give an error estimation of the method. Numerical examples are also presented to demonstrate the effectiveness of the strategy.     

基于桥梁经验数据的理论易损性曲线校准

基于理论计算或试验研究定义桥梁损伤状态建立的理论易损性曲线,通常不能将桥梁构造(包括几何性质、材料性质等)、地面运动和场地条件等因素均考虑在内.鉴于此,为更加精确地以易损性曲线的形式评估桥梁抗震性能,首先利用1994年北岭地震桥梁损伤数据建立双参数对数正态分布的经验易损性曲线;其次,给出一种多跨桥梁力学模型,定义桥墩柱转动延性值量化桥梁损伤状态,获得4种损伤状态下的理论易损性曲线;最后,以90%置信区间的经验易损性曲线对理论易损性曲线进行校准.计算结果表明:利用桥梁力学模型建立的理论易损性曲线校准后能近似吻合经验易损性曲线,且3种损伤状态阈值由SRSS优化公式得到校准.随着结构损伤知识的进展,未来可利用更详细的结构损伤过程对校准后的理论易损性曲线做二次更新,进一步提高桥梁系统风险评估的精确性,尤其是遭受强震灾害下由多座桥梁组成的高速公路网络.     

Method to accurate calibrate deposition rates of EUV multilayer coatings

Random thickness error is an important factor which effects the calibration accuracies of deposition rates for extreme ultraviolet （EUV） multilayer coatings fabricated by sputter deposition techniques. A least square fitting method is proposed to determine deposition rates and extract random thickness errors accurately. The validity of this method is shown by evaluating two deposition systems with control abilities of -0.1 nm and better than 0.01 nm respectively.     

近场光学显微镜观察到纳米尺度的折射率变化

日本京都大学研究人员用近场光学显微镜(ＮＳＯＭ)在透明的聚合物膜上制作了纳米尺度的折射率图样 ,而薄膜的透明度及表面形态均未受到严重影响 .实验中用的是 3μｍ厚的聚合物薄膜 ,它是用自转镀层法在甲苯溶液中把在聚合物 (异丁烯酸甲脂ｍｅｔｈｙｌｍｅｔｈａｃｒｙｌａｔｅ)中掺杂的 3 苯基 2 ,5 诺卜拿丁 2羧酸 (3 ｐｈｅｎｙｌ 2 ,5 ｎｏｒｂｏｒｎａｄｉｅｎｅ 2 ｃａｒｂｏｘｙｌｉｃａｃｉｄ)镀到盖板玻璃片上而成的 .折射率图样是用照明模式ＮＳＯＭ设备制作的 ,该设备具有一个剪切力尖端取样距离调节功能 ,以及一个锥形探…     

超分辨近场结构技术及其应用

超分辨近场结构(Super RENS)技术是在传统的超分辨光盘技术和近场光学的基础上发展起来的新技术。介绍了Super RENS技术的基本原理:利用掩膜层的非线性效应或表面等离子体增强效应,在近场区域可以记录、读出超过衍射极限的信号。综述了该技术在纳米光信息存储和光刻方面应用研究的最新进展,提出了存在的问题,展望了它的发展前景。     

Oscillatory disturbance in force calibration of optical tweezers

In the calibration of the optical trap stiffness, it is found that there appears an attenuating oscillation as an oscillatory disturbance added to the trapped bead movement, when the scanner is driven by a triangular wave input.An equivalent oscillator model is put forward to explain the mechanism of the oscillatory disturbance. Both the measurements and calculations show that the attenuating oscillation comes from the oscillation of the scanner and the triangular wave drive causes this additional oscillation of the scanner. Furthermore, the analysis indicates that the oscillatory disturbance will become stronger, when the stiffness of the trap increases or the natural frequency of the scanner decreases. We adopt another driving way, i.e. a sinusoidal wave input is used instead of the triangular wave input. Our experiment has verified that in this case the oscillatory disturbance is eliminated completely.     

酶标分析仪检定用中性滤光片的校准

提出酶标分析仪检定用中性滤光片的校准方法，并用校准实例对校准方法进行了验证。结合校准方法，根据JJF 1059.1—2012《测量不确定度评定与表示》建立了数学模型，不确定度的来源有测量结果的重复性、分光光度计透射比误差、分光光度计杂散辐射、中性滤光片年稳定性、中性滤光片均匀性，按该校准方法校准的中性滤光片，校准结果的不确定度为U=0.005(k=2)，校准结果能够满足JJG 861—2007《酶标分析仪检定规程》对中性滤光片不确定度U≤0.01(k=2)的要求，可用于开展酶标分析仪吸光度值的校准工作。     

Free Field Reciprocity Calibration in a Convergent Spherical Acoustic Wave of a Focusing Transducer

Based on the reciprocity theorem of the acoustic field,we derive the formula of the reciprocity coefficient of a convergent spherical acoustic wave and we calculate a series of diffraction corrective factor curves of the reciprocity coefficient of transducers.Using these formulae and corrective factors,we calibrate the free field transmitting current response and the free field voltage sensitivity of a focusing transducer using the self-reciprocity method.The experimental results of the reciprocity calibration of the focusing transducer in the frequency range of 2MHz to 5.4MHz are presented.     

基于分层抽样的校准方法分别比率-乘积估计研究

比率估计在抽样估计阶段利用辅助信息,提高了估计量的估计精度,是抽样调查中一类较为常用的估计方法,但现有的一些比率估计方法均具有各自的最优条件,这在一定程度上影响了它们在实际调查中的应用。为了解决比率估计的最优限制问题,本文引入了校准估计方法,并基于分层抽样研究了总体均值的校准方法分别比率-乘积估计量。在大样本情况下,本文推导了新估计量的估计偏差和均方误差,说明新估计量具有渐近无偏性,并在估计量均方误差最小时,得到了总体参数的渐近最优估计量和渐近最优估计量的方差。在模拟研究中,根据比率估计量的最优条件是否满足,本文生成了两种不同的总体,对比分析了新估计量和现有比率估计量的估计效果,结果表明在两种不同的情况下,新估计量的估计效果均优于现有估计量的估计效果。最后,本文利用一个实际例子,验证了新估计量的有效性和实用性。     

基于LabVIEW的电表改装与校准虚拟仿真实验的开发

虚拟仿真实验是现代实验教学的一个重要手段,它与真实实验可以紧密结合、相互补充.基于LabVIEW开发的电表改装与校准虚拟仿真实验由替代法测电流表的内阻、改装为大量程电流表、改装电压表、改装欧姆表4个实验组成,通过人机交互界面的设计、数值仿真程序设计,使学生获得与真实实验操作一致的学习体验,依据合理评价指标形成的算法规则还对学生的实验过程进行智能化的评价.该虚拟仿真实验突破了传统实验室的时空限制,极大地提高了学生物理实验的学习兴趣,促进学生动手实践.