基于迭代修正的液晶相控阵激光雷达波控数据获取

分析了影响液晶相控阵波控数据获取的几个关键因素,在此基础上通过计算期望相位面与实际相位面的相位差,提出一种基于迭代修正的波控数据获取方法,该方法可通过改变加载在液晶阵列上的参考电压或改变参考相位面实现。讨论了算法关键参数的选择。通过仿真进一步研究了液晶特性曲线范围和高斯初始相位对波控数据获取的影响。仿真结果表明:该方法能获得比较准确的波控数据;液晶特性曲线范围对波控数据的准确获取非常重要,当曲线范围较大时,液晶相控阵可补偿高斯光束引入相位的影响。     

Abel inversion using Legendre polynomials approximations

An improved Abel inversion method based on Legendre polynomials approximations is presented for reconstructing the original radial distribution of plasma emission coefficients from projected intensities. The method uses the technique of overlapping two near segments for obtaining an excellent approximation of the intensity distribution. The approximated function of the intensity profile is a combination of various shifted Legendre polynomials which in the Abel inverse equation can be integrated exactly to deduce the emission coefficient. It is shown, using simulated intensity data with and without noise inverted for a comparison with those obtained by other methods, that the method is more accurate and has a better property of noise resistance. It is well suited for applying to experimental intensities distorted by noise.     

Correct analysis of neutron-scattering data

In obtaining neutron-scattering data from deuteron experiments one encounters improperly posed problems which require corresponding treatment. A general method is presented for solving this kind of problem. The question of the stability of the solution is studied, in connection with the approximate nature of the experimental information. Stable total K⁺n cross sections are provided, by applying the preceding results, in a search for a possible Z_o resonance.     

Combined application of AES and XPS to study carbon diffusion through the selvedge of an Fe(100) surface

Diffusion of carbon from an Fe(100) surface into the bulk, following halocarbon adsorption, is modelled using experimental data from AES and XPS experi electrons (272 eV) in a dense monolayer of halogen atoms (Cl, Br) is found by a variety of experimental methods to be ～3Å, a value substantially sm inferred from the combined information provided by the AES and XPS experiments, the concentration profile of carbon perpendicular to the surface follow function. The importance of accurate data for electron escape depths and of experimental detection limits for quantitative electron spectroscopy of a s     

Shear deformation potentials in metals

The differential approach, based on the Green's function method and the muffin-tin approximation for the crystal potential, which was proposed recently as a convenient method of obtaining accurate deformation potentials in metals is discussed briefly here with particular emphasis on the relation of the method to stress-modulation experiments. Specific results are presented for the deformation potentials under tetragonal and trigonal shears of some of the states of Cu, Ag, and Au at symmetry points in the Brillouin zone, and comparison is made with available experimental data.     

中国散裂中子源反角白光中子束流参数的初步测量

中国散裂中子源(CSNS)已于2018年5月建设完工,随后进行了试运行.其中的反角白光中子束线(Back-n)可用于中子核数据测量、中子物理研究和核技术应用等多方面的实验.本文报道对该中子束的品质参数测量实验过程以及最终实验结果.实验主要采用中子飞行时间法,利用~(235)U,~(238)U裂变室和~6Li-Si探测器测量了中子能谱和中子注量率,又利用闪烁体-互补金属氧化物半导体探测系统测量了中子束斑的剖面,得到了该束线的初步实验测量结果.其中白光中子的全能谱测量范围eV—100 MeV,给出了不确定度分析;给出了中子注量率两个实验厅位置的满功率值;给出了白光中子在直径60 mm情况下的全能区束斑.通过与模拟结果的比较探讨了以上结果的合理性,并提出了改进计划.这些实验结果为以后该束线的核数据测量和探测器标定实验奠定了基础.     

Refraction of an astigmatic laser beam in a transition layer of a stratified liquid

Refraction of an astigmatic laser beam in a transition layer formed at the boundary between two liquids with different optical characteristics is studied theoretically and experimentally. An algorithm of calculating a ray trajectory in the transition layer of a stratified liquid is considered. The profile of the refractive index in the medium is modeled for three different distributions: linear, sinusoidal, and tangential. Computer modeling based on the above models allowed obtaining two- and three-dimensional images of the laser beam (refractograms) inside and outside of the medium. The influence of the beam parameters and the experimental layout on the shape of refractograms is studied, and optimal experimental conditions are determined. The experimental arrangement for detection of 2D and 3D refractograms by the laser refractography method is described. An experimental technique is developed, and digital registration of the experimental refractograms is carried out. Adaptation of special software for processing 2D refractograms allowed retrieving the refractive index profile in the transition layer of a liquid. Based on the tangential model of the diffusion layer in a saltstratified liquid, the values of the refractive index were obtained that allowed determining the salinity profile in the given layer.     

Application of the structured illumination method to study the topography of the sole of the foot during a walk

The structured illumination technique consists of projecting a fringe system onto a 3D object from a well defined space point, which results in a pattern that depends on the characteristic of the projected fringes, the viewpoint and the illuminated object morphology. Therefore, the structured illumination method enables to determine the topography of 3D objects. To implement this technique we set up an optoelectronic array that allows studying the sole of the foot during a walk. The method consists of projecting a Ronchi grid and capturing the images generated on the foot by a CCD camera. These obtained images are graphically processed and fringes converted into vectors. A depending algorithm on the experimental setup allows obtaining, from those vectors data, cotes for a discrete profile plotting of the studied object. The method enables the quantitative determination of the sole topography during the walk. Qualitatively, it can be used for diagnosis and control of deformation and injuries caused by accidents or illnesses. It can be introduced in the primary attention health system to study a great number of patients, due to its simplicity and low cost installation, and for being a non-invasive technique.     

A New 3D Digitizer by Cutting and Scanning Layer by layer

１ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｒａｐｉｄｐｒｏｔｏｔｙｐｉｎｇ,ｉｔｓｔｗｉｎｎｉｎｇｔｅｃｈｎｉｑｕｅ———ｔｈｅｒｅｖｅｒｓｅｅｎｇｉｎｅｅｒｉｎｇ［１］ｉｓｕｎｄｅｒｇｏｉｎｇａｒａｐｉｄｄｅｖｅｌｏｐ...     

A New 3D Digitizer by Cutting and Scanning Layer-by-layer

A crucial element in the reverse engineering process is to obtain 3D data of the part or its CAD model. A new method is presented in this paper, which combines layer-by-layer cutting and scanning on each cross-section of a part with a milling machine and an image scanner respectively. The method can capture the internal and external profile informations of a complex-shaped part at the same precision simultaneously. When data files of 2D edges are imported into the 3D CAD/CAM package, the 3D data or 3D CAD model is acquired. According to the customers' requirements, the system can reach the highest accuracy of 5.4 μm, and a resolution of 2.7 μm in obtaining the 2D edges. The product is completely made now, on which experiments are conducted, which demonstrate the higher accuracy and efficiency.     

Abel inversion using Legendre wavelets expansion

A new method is presented for reconstruction of the radially distributed emissivity from the line-of-sight projected intensity. The method is based on approximating the projected intensity profile by Legendre wavelets. The coefficients of the approximation are computed using the inner product of Legendre wavelets and the intensity profile. The emissivity profile is then obtained by the combination of the functions related to Legendre wavelets. The method is more accurate and noise resistant than other methods when applied to experimental data, and there is no need for a complete noise filtering of the intensity data before applying the inversion.     

A Novel Laser-Based System for Measuring Internal Thread Parameters

Based on the theory of laser measurements, we propose a novel laser-based automatic inspection system for measuring the internal thread parameters, which integrates the laser-based measuring unit to detect the longitudinal section of the thread profile and the dual-axis moving stage for the movement of an undetected object. We design a special laser probe based on the bidirectional inclination scanning method for obtaining the thread-profile data. This method and structural design enables the laser probe to overcome the shortcomings of traditional methods for measuring large inclined surfaces and eliminate the impact of the lead angle. We compare our results of internal thread-parameter measurements with the coordinate measuring machine (CMM) system and investigate the repeatability with one internal screw ring gage by the system proposed. The experimental results show that the measurement accuracy of the thread angle is 2′ and the other parameters are less than 4 μm.     

Numerical Method to Fit the Refractive Index Profile of Planar Microlenses Made by Ion Exchange Techniques

We present a fitting method for obtaining a functional form of the refractive index profile of planar microlenses made by ion exchange techniques from total shearing interferometric measurements. Compared to the usual power series expansion fit, this method allows a reduction in the number of coefficients needed to characterize a lens.     

3-D numerical modeling and simulation of nanoscale FinFET for the application in ULSI circuits

A complete three-dimensional numerical modeling of nanoscale FinFET including quantum-mechanical effects for the application in future ULSI circuits has been developed. The exact potential profile in the channel has been computed by obtaining a self-consistent solution of 3D Poisson–Schrödinger equation using Leibmann's iteration method. The threshold voltage shift, drain and transfer characteristics have been estimated and the results were compared with the device simulator and experimental results. The model is purely a physics based one and overcomes the major limitations of the existing 2D/3D analytical models by providing a more accurate result and this model is validated by comparing with the existing results as well as the experimental results.     

Obtaining the apex of the unitarity triangle from B-->piK decays

We present a method of obtaining the apex of the unitarity triangle from measurements of B-->piK decay rates alone. Electroweak penguin amplitudes are included, and are related to tree operators. Discrete ambiguities are removed by comparing solutions with independent experimental data. The theoretical uncertainty in this method is about 10%.     

利用激光散斑获取深度图

相对于普通灰度和彩色二维图像,深度图像可以得到物体的三维信息,使视觉识别和人机交互更加智能。国内外目前还没有低成本、公开的实时获取高质量深度图的方法。本文在对散斑图获取深度图原理研究的基础上,采取激光散斑的方式,运用块匹配的方法给出了一种大范围深度图的获取方法。首先,从原理上验证了块匹配方法的可行性;然后,分别从理论和实验两个方面对深度图的计算公式进行了推导和验证;再次,对深度图恢复过程进行了详细叙述,包括散斑图像的预处理和块匹配的过程;最后,给出了运用该块匹配方法得到的实验数据。实验结果表明,本文方法在物体距离相机50 cm左右时精度可以达到5 mm,200 cm时精度可以达到5 cm,可以满足室内大部分对象的识别要求。     

The decrease of light yield collection for scintillation counters of CDF muon trigger over time

The muon system of CDF spectrometer plays an important role in investigating processes with heavy quarks. The efficient functioning of scintillation counters, which comprise a considerable part of the CFD muon trigger, is a necessary condition for obtaining experimental data. The results of long-term measurements of the light yield, collected far from the photomultiplier end of the scintillation plate for different types of counters in order to predict the period of their effective operation in experiments, are presented.     

Absorption Lineshapes in Two-Dimensional Electron Spin Resonance and the Effects of Slow Motions in Complex Fluids

A methodology for obtaining pure absorption two-dimensional electron spin resonance spectra is presented for the case of large inhomogeneous broadening and/or slow motions. For slow motions, the spectra consist of “complex Lorentzians” superimposed with complex weighting factors, presenting a challenge to obtaining absorption spectra. It is shown how absorption-type spectra can be recovered for the two-pulse COSY and SECSY experiments in such cases. For three-pulse 2D ELDOR experiments, absorption lineshapes can be obtained for the autopeaks, whereas the cross peaks would be of mixed-mode character, in general. However, for practical cases the dispersive components in the cross peaks will be relatively small. Theoretical and experimental absorption spectra are provided to illustrate the method and to show the improved resolution obtained from absorption lineshapes. In particular, the variation in linewidths across a SECSY spectrum, which is a key component in elucidating motional dynamics, is clearly rendered in the pure absorption mode. A convenient method for introducing the necessary phase corrections for the slow-motional spectra is also provided.     

Tomographic inversion of measured cross-correlation functions of ocean noise in shallow water using ray theory

Based on experimental data obtained in 2012 in the Florida Strait, we study the feasibility of employing ray tomography to retrieve sound speed and flow velocity profiles from measured noise cross-correlation functions. We describe the results of numerical experiments that characterize the inversion errors resulting from peculiarities of the ray structure in shallow water, difficulties in unambiguous identification of ray arrivals, and a decrease in accuracy of ray theory at low frequencies. We show that under conditions of low-mode sound propagation, the use of the classical ray tomography scheme can yield only a rough estimate of the sound speed profile, but it allows approximate reconstruction of the current velocity profile. Application of passive ray tomography to the experimental data yields the current velocity profile in the Straits of Florida, which agrees with independent measurements within the inversion error limit.