基于线阵CCD空间滤波效应的航空相机像移速度测量方法

基于空间滤波测速原理,提出了利用线阵CCD空间滤波效应进行航空相机像移速度测量的新方法。对线阵CCD输出图像进行隔行采样,模拟了多狭缝的空间滤波特性,实现了对航空相机像移速度的光学非接触测量。通过研究空间滤波器的功率谱密度函数,对影响线阵CCD空间滤波特性的关键因素进行了特性分析,并在实验上验证了利用线阵CCD推扫图像模拟多狭缝空间滤波器测量像移速度的可行性。结果表明,对于5～53.2 mm/s范围内的像移速度,测量误差导致的像移量误差不大于1/3 pixel,能够满足航空相机像移补偿精度的要求。     

Recommender systems

The ongoing rapid expansion of the Internet greatly increases the necessity of effective recommender systems for filtering the abundant information. Extensive research for recommender systems is conducted by a broad range of communities including social and computer scientists, physicists, and interdisciplinary researchers. Despite substantial theoretical and practical achievements, unification and comparison of different approaches are lacking, which impedes further advances. In this article, we review recent developments in recommender systems and discuss the major challenges. We compare and evaluate available algorithms and examine their roles in the future developments. In addition to algorithms, physical aspects are described to illustrate macroscopic behavior of recommender systems. Potential impacts and future directions are discussed. We emphasize that recommendation has great scientific depth and combines diverse research fields which makes it interesting for physicists as well as interdisciplinary researchers.     

Imprecise expectations for imprecise linear filtering

In most sensor measure based applications, the raw sensor signal has to be processed by an appropriate filter to increase the signal-to-noise ratio or simply to recover the signal to be measured. In both cases, the filter output is obtained by convoluting the sensor signal with a supposedly known appropriate impulse response. However, in many real life situations, this impulse response cannot be precisely specified. The filtered value can thus be considered as biased by this arbitrary choice of one impulse response among all possible impulse responses considered in this specific context. In this paper, we propose a new approach to perform filtering that aims at computing an interval valued signal containing all outputs of filtering processes involving a coherent family of conventional linear filters. This approach is based on a very straightforward extension of the expectation operator involving appropriate concave capacities.     

Performance parameters and applications of a modified amplified recirculating delay line

A theoretical study of the proposed modified recirculating delay line (MARDL) is described using a time-domain analysis to derive the optical transfer function. Those cases that present novel and interesting features in the transfer function are identified. Design flexibility and tuning capabiliv, dependent on the different parameters that define the structure, are analyzed. Possible applications of the MARDL as a photonic high-selectivity filter and /or tunable notch filters are discussed.     

Off-axis electron holography of hetero-interfaces

Off-axis electron holography is one of the new emerging methods for high spatial resolution characterization of interfaces in materials. It enables recording and retrieval of both amplitude and phase of an electron wavefunction scattered by a specimen. Phase changes introduced by magnetic and electrostatic fields have been studied in the first applications of electron holography to domain walls in ferromagnetic and ferroelectric materials and to p-n junctions. Planar defects in single crystals, such as stacking faults, have been observed with strong phase contrast due to dynamical diffraction.Applications to heterogeneous interfaces have only started. High phase contrast due to mean inner potential differences is found for interfaces between high and low atomic number materials. Dynamical contributions to the phase of the transmitted beam are important for epitaxial interfaces in strongly diffracting orientations. Numerical hologram reconstructions yield quantitative amplitude and phase images of an interface which are energy filtered and are in perfect registry. Both are function of specimen thickness. The thickness dependence can be eliminated by division of the phase image with a logarithm of the amplitude image. This ratio maps the product of the mean inner potential and the mean free path for inelastic scattering across a hetero-interface in weekly diffracting orientations.Resolution enhancement through aberration correction has not been demonstrated for interfaces as yet. Holography of interfaces in plan view is unexplored.     

小波变换用于高效液相色谱的噪声滤除

根据小波变换将信号分频的性质，用Ｈａａｒ小波成功地解决了高效液相色谱中噪音的扣除问题，并应用于乳酸－稀土络合物体系的色谱数据，得到的色谱曲线平滑且峰位置不变，大葱旁氡群徒档土思觳庀蕖?     

二维滤波技术在浅地层地声信号处理中的应用

在浅层地下声探测系统中，地表直达波对物体反射波的干扰是限制探灵敏度的主要原因之一，在频率域或时间都很难将它们与反射波信号分离，本文采用二维ＦＦＴ滤波技术，利用直达波和反射波视速度的差异，在频率域和速度域进行滤波，有效地消除了直达波的干扰，提高了系统的探测灵敏度。     

利用复数核频域处理实现二值图像数学形态光学并行处理

报道了用光学频域滤波方法实现二值输入图像与复值核结构元之间的并行数学形态学操作。     

Non-Gaussian series and series with non-zero means: Practical implications for time series analysis

This paper presents a discussion of the relationship between the distribution of the input and the distribution of the output of linear filters. The purpose of the discussion is to focus attention on several fundamental aspects of developing ARIMA models which seem to be overlooked routinely in practice. The authors discuss the implications of non-normally distributed time series realizations and examine the effect of failure to estimate the constant parameter in developing ARIMA models.     

液晶光阀实时图像变换实验的新内容

以网格状物体为例。介绍了空间滤波的原理；以计算傅里叶变换全息为例，介绍了罗曼Ⅲ型和李奇型2种编码原理．利用液晶光阀图像变换光学系统进行了空间滤波实验以及计算全息图的光学模拟再现实验．实验结果与计算机仿真结果相吻合．在原液晶光阀实时图像变换实验中增加了空间滤波和计算全息2个新内容，使原实验的教学内容得到扩展．